It appears that the latest update for GTA V PC came with a performance hit due to Rockstar’s newly introduced anti-modding protections. According to the modding team responsible for LSPDFR, some scripting functions take five times longer to execute on the latest patch than it did previously.
The LSPFDR team has provided the following test, showing the performance difference between the game’s 372 and 393 versions.
Performance difference between GTA V version 372 and 393
Calling SET_CURRENT_PED_WEAPON 1000 times via ScriptHookV and RAGEPluginHook:
372: ~582ms (RPH: ~585ms)
393: ~2480ms (RPH: ~2490ms)
Performance on version 323/350 is most likely even better due to even less/no obfuscation than 372.
For what is worth, even those running the vanilla version of GTA V may witness a performance degradation due to these anti-hacking measures.
Rockstar has replied to this issue, claiming that it has “received reports of lower framerate in GTAV and GTA Online after Title Update 1.28 on PC, and we are looking into these reports now.”