@jotarodazpa I am with RTX 3090 (24 GB VRAM) / G-SYNC and I also had stuttering. It turned out it's not related to the HD texture pack but to Windows 11 and its Virtualization Based Security (VBS). I read some negative opinions about VBS and game performance and I decided to get rid of it. For my surprise this almost completely get rid of the stuttering for me.
And it's not just this game, I had massive stuttering in Kena: Bridge of Spirits (on Epic) after I upgraded to Win 11, but after I disabled VBS it's completely gone.

I don't know if you have VBS enabled, but if the answer is Yes, you may try to disable it.

@jotarodazpa I am with RTX 3090 (24 GB VRAM) / G-SYNC and I also had stuttering. It turned out it's not related to the HD texture pack but to Windows 11 and its Virtualization Based Security (VBS). I read some negative opinions about VBS and game performance and I decided to get rid of it. For my surprise this almost completely get rid of the stuttering for me.
And it's not just this game, I had massive stuttering in Kena: Bridge of Spirits (on Epic) after I upgraded to Win 11, but after I disabled VBS it's completely gone.

I don't know if you have VBS enabled, but if the answer is Yes, you may try to disable it.

@duckers_mcquack Same thing on the same hardware (Ryzen 5900x, 64 GB, RTX 3090, Win 11). No overclocked hardware. Half of my crashes happened when opening the map, game freezes and 5-10 second later CTD without a message.