Ah, the rich and famous. They're well known for their fast cars, flash clothes and inability to maintain a steady stutter-free frame-rate. At least, that's what Grand Theft Auto V is saying if recent complaints are to be believed. According to a number of players, the Ill-Gotten Gains Part 2 update has adverse side-effects—with many reporting micro stuttering and frame-rate drops since the 1.28 patch was released.
The Reddit group r/GrandTheftAutoV_PC has a highly upvoted thread about the issue, as does r/Games. The game's Steam forum is, as usual, mad as all hell—this time, though, it's overwhelmingly about the performance problems. Rockstar's own support site has acknowledged the issue. "We have received reports of lower framerate in GTAV and GTA Online after Title Update 1.28 on PC," says a new support article on the site. "We are looking into these reports now."
As for why the problems may exist, the creators of the LCPD First Response Mod claim that Rockstar has re-introduced anti-modding protection into the game. "Rockstar Games strengthened their protections against modding introduced in the first update ... This severely impacts performance, resulting in gameplay at 3 frames per second—even on some of the strongest PC systems available today."
Despite this, performance issues don't seem limited to those with mods installed. Moreover, dedicated "anti-modding" protection would seem to run counter to Rockstar's own statement on the matter back in May. It's possible that, as then, the issues could stem from an unintended side-effect—perhaps an attempt to curb GTA Online hacking, which remains a problem for the multiplayer mode.
All we have right now is speculation. We'll bring you more solid details as they emerge.