Valve enables FEX code cache in Proton Experimental for ARM

Valve has enabled the FEX code cache in Proton Experimental (ARM), which should improve 1%-low frame times and reduce stuttering on devices like the Steam Frame. FEX translates x86 code to ARM64, and the cache avoids repeated translation work.

• FEX code cache is enabled in Proton Experimental (ARM) for devices like Steam Frame
• Improves 1%-low frame times, especially over subsequent runs
• FEX runs 32-bit and 64-bit x86 apps on ARM64 Linux
• The cache stores generated ARM64 code to speed up launches and cut stutter