Good idea, that could work. But the downside it's not best reflection of block size limit impact on low-end device since we use fast CPU core/RAM rather than slow CPU cores/RAM.
Virtualbox lets you throttle CPU usage by %. Transaction verification is single threaded so you could spawn a 1-core VM from some high-end CPU like a threadripper and give the VM different usage limits. This will allow you to simulate different processor speeds (but keep in mind that Turbo Boost will cause the actual processor speed to vary greatly so in all cases capping the speed to 99% is a good idea to remove this noise).