Yes, it is expected php to be faster and your hardware-stronger
server to perform better, but there is a problem , which has to be
diagnosed, and from my experience, while troubleshooting
everything should be checked and nothing to be taken as a granted.
Sometimes the problem is right in the place you would never think
Could you share information about the php execution times for the same file on both of the servers , what are the timings ?
I'm thinking of some questions about:
1) Do you have some additional software on the new server
(ModSecurity, some firewall or things like that)
2) How is php configured to run on both of the servers (
fcgi,cgi, mod_php... ?)
3) Are the files (thumbnails) / database are locally running on
both of the servers ?
4) Are there any name resolving requests inside the PHP that
renders the thumbnail ?
Knowing the exact time php takes to process the thumbnail on both
of the servers, would be a good starting point.
You may use something as simple as this for the time measurement: