Easy way to run benchmarks quickly

General Usage Performance
1

Why does @benchmark take so long even when evals is manually specified?

using BenchmarkTools 
count = 0
@elapsed @benchmark (global count += 1; sleep(.05)) evals=1 samples=10 # 1.68
@elapsed for i in 1:count; sleep(.05) end # 0.587
count # 11
2

Does it have to do with Base.GC.gc() being called before running the test?

3

BenchmarkTools does a tuning step to figure out how many evaluations to perform; you can save these results, however, to re-use them: Manual ยท BenchmarkTools.jl

edit: sorry, just realized you mentioned evals being manually specified which would skip the tuning step. Not sure then; maybe the GCing explains it like you said.