Interspire Email Marketer upgrade slows import process

Hi Guys,
Have you noticed when doing PHP upgrade to 5.5.38 from 5.3 version and upgrading new 6.1.6 version of Interspire, upload process is way too slow. Before it was super quick like 100+ records / second.
Any advise where should be problem?
Have you noticed when doing PHP upgrade to 5.5.38 from 5.3 version and upgrading new 6.1.6 version of Interspire, upload process is way too slow. Before it was super quick like 100+ records / second.
Any advise where should be problem?