Uninstalling an update that addresses a security vulnerability like Spectre or Meltdown sounds like a bad idea. But if the alternative is a PC that constantly crashes, you might be happy to take the small risk in exchange for stability. For Windows users, Microsoft now offers a patch that reverses Intel's microcode fix, but you won't find it via Windows Update.
Here's Microsoft's reasoning for the hotfix:
...Intel noted that this microcode can cause “higher than expected reboots and other unpredictable system behavior” and then noted that situations like this may result in “data loss or corruption.” Our own experience is that system instability can in some circumstances cause data loss or corruption. On January 22, Intel recommended that customers stop deploying the current microcode version on affected processors while they perform additional testing on the updated solution.
The patch works for Windows 7, 8.1 and 10. Again, if you're not experiencing crashes or the like, then there's no need to download this update.
Update to disable mitigation against Spectre, Variant 2 [Microsoft, via gHacks]