There were actually performance complains. I didn't encounter any problems myself though. I had one or two instances with a lot of NPCs, where the performance dropped a little bit, but nothing serious.
About to make a very unpopular comment.
A lot of the performance issues we see with BG3 and other RPGs can be faulted to Youtube hardware reviewers.
For years these reviewers have focused on GPUs for gaming and CPUs for work and have perpetuated a belief that the GPU is the end all item for a gaming rig. A PROPER gaming rig is balanced with the CPU, GPU RAM and storage all taken into account to create a gaming PC. Gaming is not about one component but rather the sum of it's parts.
Youtubers have focused on games that are GPU limited and real, deep RPG play gets a backseat if explored at all. Deep RPGs, especially CRPGs will not be as GPU heavy and even start leaning into the CPU a lot. This is where things break down... Gamers and Devs have seen tons of influencers pushing GPU as the be all end all of gaming and so put the focus there and this means gamers build with weaker CPUs and Devs optimize toward the GPU.
In the optimization arena, even now most games do not utilize more than 4 cores or so. This needs to be opened up, 6 core 12 thread processors are fairly common, instead of optimizing CPU performance to single or small thread counts, open those suckers up, let us use those 6 cores and 12 threads.
In the gamer area, we need to stop looking for how cheap we can do the CPU. A great gaming system, not built with wads of cash, is a balancing act where the sum of the parts matters more than the specific part. AMD at least is making an effort to give gamers a leg up with the X3D lineup.