In the v8v7 test, qjs-ng's performance lags behind qjs

[ahaoboy]

https://ahaoboy.github.io/js-engine-benchmark/?selectEngines=quickjs,quickjs-ng

I used the default qjs build configuration and a precompiled version of qjs-ng . I ran the v8v7 test in GitHub CI and recorded the results. I found that qjs-ng consistently lagged behind qjs by about 10%.

Is this due to differences in the build options? Or has qjs-ng introduced some features that have led to performance degradation?

The v0.10.1 version on the Ubuntu platform seems to be more obvious

I also reproduced this problem in VirtualBox virtual machine

{
  "Version": {
    "quickjs": "2025.04.26",
    "quickjs-ng": "0.10.1"
  },
  "Total size": {
    "quickjs": 4476160,
    "quickjs-ng": 2068408
  },
  "Exe size": {
    "quickjs": 4476160,
    "quickjs-ng": 2068408
  },
  "Dll size": {
    "quickjs": 0,
    "quickjs-ng": 0
  },
  "Richards": {
    "quickjs": 1021,
    "quickjs-ng": 946
  },
  "DeltaBlue": {
    "quickjs": 975,
    "quickjs-ng": 931
  },
  "Crypto": {
    "quickjs": 1371,
    "quickjs-ng": 594
  },
  "RayTrace": {
    "quickjs": 1388,
    "quickjs-ng": 1059
  },
  "EarleyBoyer": {
    "quickjs": 2347,
    "quickjs-ng": 1989
  },
  "RegExp": {
    "quickjs": 354,
    "quickjs-ng": 242
  },
  "Splay": {
    "quickjs": 2548,
    "quickjs-ng": 2385
  },
  "NavierStokes": {
    "quickjs": 2389,
    "quickjs-ng": 1469
  },
  "Score": {
    "quickjs": 1326,
    "quickjs-ng": 992
  },
  "Score/MB": {
    "quickjs": 310,
    "quickjs-ng": 502
  },
  "Time(s)": {
    "quickjs": 35,
    "quickjs-ng": 47
  }
}

[nickva]

Didn't look in detail at the benchmark but noticed a recent large discrepancy in performance between qjs and qjs-ng especially with the code used in yt-dlp was related to string concatenation bellard/quickjs#445 (comment)

In that particular case it was the string rope optimization and it was about an 80x slowdown. It looks like that optimization may be coming to quick-ng soon #1002 (comment)