Dell XPS 15 9500

Sorry, mistyped. I meant Hyperthreading, not multithreading. For context:

Safe use of Hyperthreading when Xen stable includes new sched-gran parameter · Issue #5547 · QubesOS/qubes-issues · GitHub

Hyperthreading (should) be disabled in Qubes (for security reasons), even if enabled in BIOS. For some reason though, disabling it in BIOS fixes the Suspend issue.