I suspect that's due to the GPU and not due to Prism, because they basically just took a mobile GPU and stuffed it into a laptop chip. Generally performance seems to be on par with whatever a typical flagship Android devices can do.
Desktop games that have mobile ports generally seem to run well, emulation is pretty solid too (e.g. Dolphin). Warcraft III runs OK-ish.
The GPUs don't go toe-to-toe with current gen desktop GPUs but they should be significantly better than the GTX 650, a mid range desktop GPU from 2012, the game (2019) lists as recommended. It does sound like something odd is going on than just lack of hardware.
That something odd is called GPU drivers. Even Intel struggled (they recently announced that they are dropping all gpu driver older than Alchemist development) to get games running on their iGpus
Desktop games that have mobile ports generally seem to run well, emulation is pretty solid too (e.g. Dolphin). Warcraft III runs OK-ish.