Performance Bug Finder
Find slow code and performance bottlenecks fast
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Why was your page fine last month and slow today? Profilers point at a line, logs point at a timestamp, and neither one tells you why the loop underneath does ten times the work it needs to. Performance Bug Finder reads the code you paste and names the pattern that is costing you the time.
Short answer: Performance Bug Finder is a free AI tool that reads pasted code for slow patterns such as queries inside loops, then explains the root cause, shows a corrected version and suggests how to stop the problem returning.
What is Performance Bug Finder?
Performance Bug Finder is a debugging tool on EizTools that reads code you paste and points at whatever is making it slow: a query inside a loop, a list rebuilt on every pass, a whole file loaded into memory when one line at a time would do.
It reads, it does not run. Performance Bug Finder has no profiler, no access to your server and no view of your data, so it reasons from the code in front of it. That works for problems visible in source, and not at all for a slow disk.
Where Slow Code Usually Hides
Three situations come up constantly, all visible in source.
| Symptom | What it usually turns out to be | What to paste |
|---|---|---|
| An admin list page takes eleven seconds | A query running once per row instead of once | The controller plus the model it loops over |
| The nightly CSV import gets slower every month | The whole file loaded into memory first | The import function and how the file is opened |
| A table freezes on every keystroke | Work repeated on every render | The component and the state it depends on |
A service allocating a fresh object per request in a hot path fits the same shape.
How Does Performance Bug Finder Work?
Paste the slow code into the prompt box and say what slow means in your case. Pick a model, then open advanced options.
Set Issue Type to Performance so the review stays on speed. Analysis Depth starts on Standard, which suits a single function. Move to Deep when several pieces are involved. Output set to Root Cause gives the explanation alone, while Fix + Explanation returns corrected code with the reasoning beside it.
Explain Root Cause, Provide Fixed Code and Suggest Prevention are already on, and the Thoroughness slider starts at 70 percent. Show Test to Reproduce is off. Switch it on when you want a failing test before you change anything.
Important Measure before and after with your own timer. A version that reads better is not automatically faster, and only your numbers settle it.
Paste Less Code, Get A Sharper Answer
The answers improve as the input gets narrower.
- Send the slow function and its caller, not the whole file. Code that never runs is noise.
- Say what you measured. Half a second on ten rows and eleven seconds on ten thousand is the most useful line in the prompt.
- Name the data size. A loop over twelve items and a loop over twelve million are different bugs.
- List what you already ruled out in Custom Instructions, so the answer does not repeat your own work.
What works well
- Names the pattern, not just the line, so the fix carries further
- Explains the cost in words a reviewer will accept in a pull request
- Strong on the classics: repeated queries, work redone in loops, string building
What to watch for
- It never runs anything, so it cannot rank two fixes by real timing
- It sees only your snippet, so a slow dependency two layers down is invisible
- Query speed depends on indexes and row counts it has no way to check
On EizTools every tool is free with no account needed, and you choose which AI model handles the request from the selector above. The tools sit next to each other by job, so when the trouble is a broken function rather than a slow one, Error Fixer is the page to take it to.
Frequently Asked Questions
Can it profile my application?
No. It has no timer, no profiler and no access to your running process. It reads the code you paste and reasons about the work that code does, so your own measurements still decide.
What does Analysis Depth change?
Quick returns a short verdict on the obvious problem. Standard, the default, works through one function properly. Deep follows the call path across everything you pasted and takes longer to come back.
Will it rewrite the slow part for me?
Yes. Provide Fixed Code is on by default, so a corrected version arrives with the explanation. Treat it as a suggestion, since it was written without sight of your tests or your data.
Can it tell me why a database query is slow?
Only from what the code shows, such as a query inside a loop or a missing limit. Index choices and row counts stay invisible to it, so confirm anything it says with your own EXPLAIN plan.
Slow code rarely announces itself. It costs a little more every month until somebody finally opens the file. Paste the function you suspect into the box above, say what you measured, and start from a named cause.
Sabir Bepari
Founder of EizTools and a passionate AI enthusiast dedicated to building practical, user-friendly AI tools that simplify everyday tasks.
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