Cutting to the chase, I propose you add settings to disable character renders on the inventory and/or party screens. Perhaps something like the following.

Party screen character render:
  • On
  • Disable effects
  • Silhouette / Sprite
  • Off

Inventory screen character render:
Same options as above.

I assume it's fairly obvious that the inventory and party screens can contribute towards performance issues. Or at the very least, I assume most people notice that the party screen is generally less responsive than the inventory screen. I'd wager that the character model displayed in the screens is the primary culprit. Especially when characters have conditions with particle effects.

My recommendation, to help out those of us with potato PCs, is to copy what other games usually do to mitigate this issue: offer a settings option to simply display less stuff. As a reference, when PUBG implemented this setting the performance difference was night and day for many people.

I was originally thinking a boolean on/off toggle setting would be enough, and it definitely would be better than nothing, but I included a more expansive list of options in my suggestions above because it would be nice to have that granularity if possible. Heck, even adding only boolean toggles to enable/disable effects on the party / inventory screen renders would be better than nothing. Personally, I only started to avoid the party screen after my characters accrued a number of particle effects from things like longstrider, act 2 conditions, etc..