coraza consumes too much cpu resources, can we do performance optimization

[Axkea]

Here are the flame charts I generated during my performance tests, which can be used as a reference for performance optimization
https://drive.google.com/file/d/1965ETYFolv62OFfA6SqKKFfoT-bIc60j/view?usp=drive_link

[Axkea]

This is the top 10 for pprof （cpu）
(pprof) top
Showing nodes accounting for 16520ms, 46.35% of 35640ms total
Dropped 352 nodes (cum <= 178.20ms)
Showing top 10 nodes out of 137
flat flat% sum% cum cum%
3410ms 9.57% 9.57% 6270ms 17.59% regexp.(*Regexp).tryBacktrack
3180ms 8.92% 18.49% 5180ms 14.53% regexp.(*machine).add
2400ms 6.73% 25.22% 2400ms 6.73% [envoy]
1330ms 3.73% 28.96% 3300ms 9.26% runtime.scanobject
1250ms 3.51% 32.46% 2770ms 7.77% regexp.(*machine).step
1220ms 3.42% 35.89% 26570ms 74.55% github.com/corazawaf/coraza/v3/internal/corazawaf.(*Rule).doEvaluate
1200ms 3.37% 39.25% 1860ms 5.22% runtime.findObject
890ms 2.50% 41.75% 890ms 2.50% regexp.(*bitState).shouldVisit (inline)
830ms 2.33% 44.08% 3640ms 10.21% runtime.mallocgc
810ms 2.27% 46.35% 920ms 2.58% regexp.(*bitState).push (inline)

[jcchavezs]

cc'ing @anuraaga as he worked in allocations, performance and GC.

[anuraaga]

This looks to mostly be showing regexp processing in the flame graph. It is known that Go's regexp is slow

golang/go#26623

An alternative is to use coraza-wasilibs with re2

https://github.com/corazawaf/coraza-wasilibs

While the Wasm codepath has issues with concurrency until Wasm threads proposal reaches stage 4, it looks like you are using cgo already, in which case you can install re2, e.g. apt-get install libre2-dev, and use the re2_cgo build tag to activate the cgo path. I think it will improve your performance.