It seems Monster Hunter Wilds has performance issues even on Sony's latest hardware, with an early analysis indicating the game is struggling to maintain a consistent 30FPS.

According to French outlet GamerSyde, Monster Hunter Wilds on the PlayStation 5 Pro forces players to choose between different display modes, and when Resolution mode is selected, the game targets 30FPS and doesn't come with an option to disable raytracing, which, if disabled, would give more performance. Moreover, Resolution mode uses PSSR to upscale from a native resolution of 3072 x 1728p to 4K, and even with PSSR upscaling technology, Monster Hunter Wilds still isn't able to hit a consistent 30FPS on the PS5 Pro. GamerSyde speculates the inconsistent framerate or frequent drops in FPS are a result of incorrect frame pacing.
Moving to Balanced and Performance modes. Balanced mode hits an upscaled resolution of 2496 x 1404p and also doesn't have an option to disable raytracing. The report states the framerate in this mode is also quite inconsistent, with frequent spikes that can make the image lose quality. As for Performance mode, the early analysis found the PS5 Pro is capable of reaching 60FPs, but to achieve this framerate, the image quality has to be significantly reduced. The image quality hit can be attributed to PSSR struggling to upscale from the mode's native resolution of 1080p.
Unfortunately, it seems that Monster Hunter Wilds will require some updates before it reaches a point where performance can be considered stable.