I know that setting `COMPLUS_ZapDisable=1` will "disable debugging optimizations in Visual Studio," but I can't seem to find any references that tell me what that actually means. 

* What features/functionality are actually disabled by this setting?
* What are the ramifications of always using this setting?
* If the cost is that "[debugging] runs a bit slower," can we try to elaborate a bit? Is the difference significant? Does that difference scale with project size? Is it unbearable on larger projects? Etc.
	+ *I know this one is a bit more vague, but explanation is really what I'm after*
* Is there an actual known reason why this isn't set by default?
	+ *While opinions are welcomed, I'm really wondering about if there is a factual, known issue that disabling this setting by default addresses*