I'm missing the point how changing the user agent resolves the delay? It is quite possible that this was an attempt to hinder ad blocking but why would changing

I'm missing the point how changing the user agent resolves the delay? It is quite possible that this was an attempt to hinder ad blocking but why would changing the user agent to Chrome while maintaining all of the same ad blockers remove the slowdown? I actually still think that there is a decent change that this wasn't fully intentional (as in the task wasn't to user-agent detect non-Chrome and slow it down) but the explanation doesn't cover why this delay depends on the user agent?