What is plugin delay compensation?

[Rakib]

Yes, the topic said it, most sequenser have it, renoise have it. But what does it do?

[psishock]

In a nutshell, if any VST(i) makes an unwanted latency delay, that technology fixes the problem with a bit "reading ahead" on the pattern rows or sequences, and you will not experience any more (short or longer) ones, the note will play at the exact wanted time, precisely.
Its a good stuff, could help with crappy coded vst(i)s example.