This compiler's strangely deep and slow (6)
I believe the answer is:
impede
'slow' is the definition.
(I've seen this before)
'this compiler's strangely deep' is the wordplay.
'this compiler's' becomes 'im' (I've seen this in other clues).
'strangely' indicates an anagram.
'deep' is an anagram of 'pede'.
'im'+'pede'='IMPEDE'
'and' is the link.
(Other definitions for impede that I've seen before include "Delay, be an obstacle" , "Hinder or obstruct, say progress" , "Interfere with progress" , "Block progress of (something)" , "Put obstacle in the way, hinder" .)