Help - Admin panel all of the sudden takes 2 minutes to load each page. Frontend < 1 second.

[bluelabel]

I have a magento site that's been running 1.8.1 for several months. The site has been working great until Saturday customers aren't able to checkout due to "Unable to communicate with Paypal Gateway". At the same time my admin panel is out of nowhere taking 85-140 seconds to load each page.

Things to note:

- Frontend pages are blazing fast - < 1 second to load. Only admin panel pages are affected

- There have been no code changes to the site in months

- Log tables have been truncated

- On a Dedicated server w/ memory limit of 1024mb (was 512mb *troubleshooting*)

Not sure if there is something wrong on the hosting end or not but I have absolutely no clue about this. Been trying everything and can't seem to track down the issue. Not sure if it's on the server end?

Thought it might be something with my SSL since Paypal was rejecting my payment request, but I disabled secure URL's for the admin panel and it still takes ages to load.

[JLHC]

It sounds like this may be a connection issue with PayPal. 

Is your SSL Certificate compliant with PayPal's latest requirement - SHA-256 algorithm and 2048-bit G5 certificates?

You may also want to enable Magento profiler to identify what is slowing the loading speed down. Just make sure to disable it once you are done (as it's not supposed to be enabled in a production environment, only for troubleshooting). 

[MagenX]

always enable Aoe_profiler in this situations,

we had the same problem before, and we found that one extension was trying to connect to its server for upgrade check, but that server was down.

[bluelabel]

I think I am having some sort of problem with the DNS per my research?

My log shows the following error:

exception 'Exception' with message 'PayPal NVP CURL connection error #6: Couldn't resolve host 'api-3t.paypal.com'' in /home/carter/public_html/app/code/core/Mage/Paypal/Model/Api/Nvp.php:986

[bluelabel]

I have also done profiler and I wasn't able to find the issue that way. Said there was a bottle neck in the routers, but I truncated the routers table already.

DISPATCH EVENT:controller_action_predispatch is also showing a bottleneck.