More info on : https://ant-sh.blogspot.com/2020/07/gta-4-stutter-choppiness-fix.html#_Toc45820767

Using any value above 3072.0 on latest Complete Edition version is not recommended as it seems to cause texture popping all throughout the map

DXVK may at first be laggy as it builds state cache, it is normal - the more you play the smoother it will become e.g. do several missions or run built-in benchmark
at least 3 times and you will see.
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Installation : Drag and drop the files into your Grand Theft Auto IV folder.
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Credits to Anton Shabunin (https://ant-sh.blogspot.com/).