The site is taking 1 min to load up on the first request after upgrading from 4.0 to 4.5.3

Got Serious Problem After Upgraded to Latest Version.

We've upgraded from 4.0 to 4.5.3 and moved all customization to plugins. and site is taking 1 min to load page on first request.

We have both Preload Enabled and AlwaysRunning, and app startup is 15 seconds but the first visit is still 60 seconds.

We also tried to unload Customer plugins & nop-template plugins and also tried with default nop with our upgraded db. still result is same.

no error in logs.

Here is miniprofiler report.

_Root.cshtml is taking 54 sec+

1. So what theme are you using?
2. How is it loaded with a default theme?

1. Its custom css on default theme
2. Yes we tried with default nop + default theme with upgraded db and still same result.

Do you experience the same slowness on a default clean installation (without any customization)?

If no, then obviously it's related to some wrong customization

Yes we tested with default nop clean with our upgraded db and still same result.

if i will test with default nop clean with default db then no issue. because there is no more data. So its not customization issue.

Something is wrong with preparing data when nothing in cache then after things are fast.

Moreover, If we comment footer then also site getting open fast on first visit.

If you guys really want to look on deeply. I can share site detail on PM.