[1] https://css-tricks.com/test-your-product-on-a-crappy-laptop/
If you’re willing to build some infra, there’s probably a lot more you can do—nightly slow-hardware runs come to mind immediately, browser devtools have a convincing builtin emulation of slow connections, a page displaying a graph of test runtime over time[1] isn’t hard to set up, etc.—but I don’t really have experience with that.
[1] See e.g. https://arewefastyet.com/win11/benchmarks/overview?numDays=3....
Even if you don’t fix them, knowing where the weak points are is valuable for when they do snap in production.
Similarly, a colleague I had before insisted on using a crappy screen. Helped a lot to make sure things stay visible on customers’ low contrast screens with horrible viewing angles, which are still surprisingly common.