I found that these type of drops simply comes from the host machines' related running applications or hardware.
1 I found a very common culprit; from the windows task manager, the Malware service executable.
These, and other processes that come up unexpected; when they are actually expected to run, often cause overall performance dips.
In combination with this, if your processor heats up, it can cause freezes too.
As a test, you could have another computer run your projects to see if your computer might be heating up or having some other sort of cpu intensive activity going on.