Prestashop TTFB really slow on Mac? (Hook processing displayTop)

[codei]

I have a bizarre problem:

 

My site is loading very slowly but only on certain browsers. It loads in 10 seconds on chrome on my Mac and under 4 seconds on Chrome on my PC. The real mystery is that it seems that it's a server issue, not a browser issue.

 

From the profiler, it looks like Hook processing takes over 6 seconds on Mac/Chrome. On PC/Chrome it only takes 71ms. Memory peak usage on Mac/Chrome is 25.1 Mb and only 16.5 on PC/Chrome. SQL Queries on Mac/Chrome is 842 queries whereas on PC/Chrome it's only 125. This is the same page. It doesn't make any sense:

 

 

PC:

 

 

Anyone have any ideas as to what's happening?