# Benchmarking with @time @btime and subsequent runs return shorter execution time

**URL:** https://discourse.julialang.org/t/benchmarking-with-time-btime-and-subsequent-runs-return-shorter-execution-time/52580
**Category:** New to Julia
**Tags:** benchmark, benchmarktools
**Created:** [December 29, 2020, 5:47pm UTC](https://discourse.julialang.org/t/benchmarking-with-time-btime-and-subsequent-runs-return-shorter-execution-time/52580 "2020-12-29T17:47:27Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [December 29, 2020, 9:49pm UTC](https://discourse.julialang.org/t/benchmarking-with-time-btime-and-subsequent-runs-return-shorter-execution-time/52580/4 "2020-12-29T21:49:52Z")

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In my not so long experience, I would say that 4% of GC is not necessarily an indication of a problem, but it may be. I had a similar situation and in my case I finally found where those allocations where occuring and fixed them, making the threaded version much better. Ideally one would like a code that does not allocate anything in the performance-critical parts.

I would try to track those allocations and be sure that they are strictly necessary.

Take a look at this thread: [Track memory usage](https://discourse.julialang.org/t/track-memory-usage/52158)

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