# How to Talk About Performance and Speed in English at Work

> Learn to discuss latency, throughput, and response time in English. Master performance vocabulary for design reviews, postmortems, and stakeholder communication in tech workplaces.

- **Author:** Speak Tech English
- **Published:** 2026-08-28
- **Updated:** 2026-09-07
- **Topic:** [Email & Slack](https://app.speaktechenglish.com/knowledge-base/topic/email-slack.md)
- **English level:** C1
- **Guide:** https://app.speaktechenglish.com/knowledge-base/how-to-talk-about-performance-and-speed-in-english

## Short answer

When discussing system performance in English, use precise terms: latency (delay before transfer begins), throughput (data processed per unit time), response time (total time from request to response). For stakeholders, translate technical metrics into business impact: 'Page load times increased by 2 seconds, which historically reduces conversion by 7%.'

## When Systems Speed Up: Verbs for Performance Gains

When performance improves, we need precise verbs to describe the change. In tech contexts, we adapt everyday 'speed' vocabulary to describe metrics, deployments, and system behaviour.

Use **accelerate** for gradual performance gains: 'After we migrated to the new CDN, page loads accelerated significantly.' Note that accelerate implies a continuous improvement curve, not a sudden jump.

Use **rocket** and **soar** for dramatic improvements—these verbs carry positive connotations and work well in executive summaries: 'Throughput rocketed after we optimised the database queries.' 'Response times soared past our Q3 targets.' (Note: when we say response times 'soared past targets,' we mean the performance exceeded expectations, not that times increased.)

For describing quick fixes during incidents, use **zip** informally: 'The hotfix zipped through QA and hit production in under an hour.'

| Verb | Tech Usage | Example Sentence |
| --- | --- | --- |
| accelerate | Gradual performance improvement | Query performance accelerated after we added the index. |
| rocket | Dramatic metric improvement | Our Lighthouse scores rocketed from 45 to 92. |
| soar | Positive upward trend | User satisfaction soared after we reduced latency. |
| zip | Fast deployment/process (informal) | The PR zipped through review in ten minutes. |

> **Grammar Note: Transitive vs Intransitive:** Accelerate can be both transitive and intransitive: 'We accelerated the deployment' (transitive) vs 'Deployment times accelerated' (intransitive). Rocket and soar are intransitive only—you cannot say 'We rocketed the metrics.'

## When Systems Slow Down: Describing Degradation

Describing performance problems requires careful verb choice. The severity of the issue should match your vocabulary.

Use **crawl** for severely degraded but functional systems: 'The API is crawling—responses are taking 30 seconds.' This verb emphasises painful slowness while indicating the system hasn't completely failed.

Use **creep** for gradual degradation over time: 'Memory usage has been creeping up since the last release.' This verb suggests a slow, almost unnoticeable increase that accumulates into a problem.

Use **plummet** and **plunge** for sudden, severe drops: 'After the config change, throughput plummeted by 80%.' These verbs convey urgency and are appropriate for incident communications.

Use **slump** and **tumble** for significant but less catastrophic declines: 'Cache hit rates slumped during peak hours.' These are useful in postmortems when describing concerning but manageable degradation.

| Verb | Severity | Tech Context Example |
| --- | --- | --- |
| crawl | Severe (ongoing) | Database queries are crawling under the current load. |
| creep (up/down) | Gradual | Latency has been creeping up over the past sprint. |
| plummet | Sudden, catastrophic | Availability plummeted to 60% during the outage. |
| plunge | Sudden, severe | The service plunged into an error state. |
| slump | Significant decline | Request success rates slumped after the deployment. |
| tumble | Rapid decline | Our SLO compliance tumbled below acceptable thresholds. |

> **Cultural Note: Choosing Severity in Incident Calls:** In incident calls, match your verb intensity to the actual impact. Saying throughput 'plummeted' when it dropped 5% can make you seem alarmist. Reserve dramatic verbs for genuine emergencies to maintain credibility.

## Core Performance Vocabulary: Latency, Throughput, and Response Time

Three terms form the foundation of performance discussions. Understanding their precise meanings helps you communicate accurately in design reviews and postmortems.

| Term | Definition | Example Usage |
| --- | --- | --- |
| latency | Time delay before data transfer begins (often measured in milliseconds) | We need to reduce latency between our EU servers and US users. |
| throughput | Volume of data or requests processed per unit of time | The new architecture handles 10x the throughput of the legacy system. |
| response time | Total time from request initiation to complete response | P99 response times exceeded 500ms during the incident. |
| SLA (Service Level Agreement) | Contractual performance commitment | Our SLA guarantees 99.9% uptime and sub-200ms response times. |
| SLO (Service Level Objective) | Internal performance target | We're tracking against an SLO of P95 latency under 100ms. |
| P99/P95 | 99th/95th percentile of measurements | P99 latency is more meaningful than averages for user experience. |

- Latency focuses on the DELAY before anything happens—think of it as waiting time.
- Throughput focuses on VOLUME over time—how much work the system handles.
- Response time is END-TO-END—the complete user-perceived duration.
- SLAs are EXTERNAL commitments; SLOs are INTERNAL targets.

## Scenario: Explaining Performance Issues to Non-Technical Stakeholders

When discussing performance with product managers, executives, or customers, translate technical metrics into business impact. Avoid jargon and focus on user experience and business outcomes.

| Too Technical | Stakeholder-Friendly |
| --- | --- |
| P99 latency spiked to 2000ms due to connection pool exhaustion. | Page loads slowed significantly—about 1 in 100 users waited over 2 seconds, which typically causes drop-offs. |
| Throughput plummeted when the read replicas fell behind. | The system couldn't handle the traffic volume, so some users experienced errors or slow responses. |
| We're breaching our SLO on the checkout endpoint. | Checkout is slower than our target, which may be affecting conversion rates. |
| Memory usage has been creeping up, indicating a potential leak. | We've spotted early signs of a problem that could slow things down if we don't address it soon. |

> **Phrase Bank: Connecting Metrics to Business Impact:** Use these bridging phrases: 'This translates to...', 'In practice, this means...', 'For our users, this looks like...', 'Historically, this level of degradation correlates with...'

## Scenario: Discussing Performance in Design Reviews

In design reviews and RFCs, you need to discuss performance requirements, trade-offs, and expectations precisely. Here's vocabulary for these technical discussions.

| Phrase | Context | Example |
| --- | --- | --- |
| under load | Describing performance at scale | How does this approach perform under load? |
| at the cost of | Discussing trade-offs | We gain throughput at the cost of increased latency. |
| scales linearly/logarithmically | Describing growth patterns | Memory usage scales linearly with connection count. |
| degrades gracefully | Failure mode discussion | The circuit breaker ensures the service degrades gracefully. |
| within acceptable thresholds | SLA/SLO compliance | P95 response times remain within acceptable thresholds. |

| Informal (Slack/Standup) | Formal (RFC/Design Doc) |
| --- | --- |
| This should be way faster than what we have now. | This approach should reduce P95 latency by approximately 40%. |
| It might get slow if we get hammered with traffic. | Performance may degrade under sustained load exceeding 10k RPS. |
| We're basically trading speed for consistency here. | This design prioritises throughput at the cost of strict consistency. |
| The fallback kicks in if things go sideways. | The circuit breaker activates when error rates exceed the configured threshold. |

## Scenario: Writing a Postmortem About a Performance Incident

Postmortems require precise, blameless language that accurately describes what happened. Choose verbs that convey the severity and nature of the incident without dramatisation or understatement.

- Use **plummeted/plunged** for sudden, severe degradation: 'Availability plummeted to 73% at 14:32 UTC.'
- Use **crawled** for sustained poor performance: 'API responses crawled, with P99 exceeding 15 seconds.'
- Use **careered** (British) for out-of-control escalation: 'The cascade failure careered through dependent services.'
- Use **crept** for gradual degradation that preceded the incident: 'Memory usage had been creeping up for several days before the OOM event.'
- Use **rocketed/soared** for recovery: 'After the fix deployed, success rates rocketed back to 99.9%.'

| Vague (Avoid) | Precise (Use) |
| --- | --- |
| Performance got bad. | P99 response times plummeted from 150ms to 4500ms. |
| Things slowed down gradually. | Latency crept up by 50ms per hour over the preceding 6 hours. |
| The system couldn't keep up. | Throughput tumbled to 20% of baseline capacity. |
| We fixed it and things got better. | After the hotfix deployed, response times accelerated back to baseline within 3 minutes. |

> **Culture Note: Blameless Postmortems:** In blameless postmortem culture, focus on systems and processes, not individuals. Say 'The deployment process allowed the misconfiguration to reach production' rather than 'Someone deployed a bad config.' Your verb choices should describe events, not assign fault.

## Common Mistakes: What We Hear vs Better English

| Heard at Work ❌ | Better English ✓ |
| --- | --- |
| The latency rocketed to 500ms. | The latency spiked to 500ms. (Rocket implies positive movement; latency increasing is negative.) |
| Response times are very slow. | Response times are crawling. / Response times have degraded significantly. |
| The performance plunged up. | Performance soared. / Metrics rocketed. (Plunge is always downward.) |
| Throughput creeped up. | Throughput crept up. (Crept is the correct past tense.) |
| We need to speed up the latency. | We need to reduce the latency. (Latency is a measurement—you reduce it, not speed it up.) |
| The SLA breached. | We breached the SLA. / The SLA was breached. (SLA doesn't breach itself—it's breached.) |

> **Grammar Trap: Creep → Crept (Not Creeped):** The past tense of 'creep' is 'crept,' not 'creeped.' This is a common error even among native speakers. Similarly: 'The bug crept into production,' not 'creeped into production.'

## Pronunciation Guide: Key Performance Terms

Mispronouncing technical terms can undermine your credibility in meetings. Here's how to pronounce key performance vocabulary correctly.

_This guide has interactive exercises on the page: https://app.speaktechenglish.com/knowledge-base/how-to-talk-about-performance-and-speed-in-english_

## FAQ

### What's the difference between latency and response time?

Latency measures the delay before data transfer begins—the waiting time. Response time measures the complete duration from request initiation to receiving the full response. In practice, response time includes latency plus processing time plus data transfer time.

### How do I explain a performance incident to non-technical stakeholders?

Translate metrics into business impact and user experience. Instead of 'P99 latency spiked to 2000ms,' say 'Page loads slowed significantly—about 1 in 100 users waited over 2 seconds, which typically causes drop-offs.' Use bridging phrases like 'In practice, this means...' and 'For our users, this looks like...'

### What verbs should I use for dramatic performance improvements?

Use 'rocketed' and 'soared' for dramatic positive changes: 'Throughput rocketed after the optimisation' or 'User satisfaction soared.' These verbs convey enthusiasm and significant improvement, making them ideal for executive summaries and team celebrations.

### What's the correct past tense of 'creep' in performance contexts?

The correct past tense is 'crept,' not 'creeped.' Say 'Memory usage crept up over the past week' or 'The bug crept into production.' This is a common error even among native speakers.

### How formal should my language be in a postmortem document?

Postmortems require precise, blameless language. Use specific metrics ('P99 response times plummeted from 150ms to 4500ms') rather than vague descriptions ('performance got bad'). Focus on systems and processes rather than individuals, and choose verbs that accurately convey severity without dramatisation.

### Is 'SLA' pronounced as a word or spelled out?

SLA is spelled out as individual letters: 'S-L-A' (/ˌes.elˈeɪ/). Do not try to pronounce it as a word like 'slah.' The same applies to SLO ('S-L-O').


## Related

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- [How to Describe Scale and Complexity in English at Work](https://app.speaktechenglish.com/knowledge-base/how-to-describe-scale-and-complexity-in-english.md)
- [How to Handle Words With Multiple Meanings in English at Work](https://app.speaktechenglish.com/knowledge-base/how-to-handle-words-with-multiple-meanings-in-english.md)
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- Cite as: "Speak Tech English — How to Talk About Performance and Speed in English at Work. https://app.speaktechenglish.com/knowledge-base/how-to-talk-about-performance-and-speed-in-english. Audience: non-native English speaking software engineers and tech professionals (level C1).".