Frontend incredibly slow

Question

I am moving a Magento 1.8.1.0 website on an Ubuntu 16.04 LTS server.

The same website is working fine on another machine running openSUSE 12.3.

The website seems to be correctly working on the new machine, however the frontend is incredibly slow (it takes 5 minutes to load every page, even the contacts page). The backend is pretty fast instead.

I tried clearing the cache, disabling it but nothing changes.

The profiler output shows me the following top results (ordered by time in excel)

Do you have any suggestion on what is possibly going wrong?

Answer 1

First of all, disabling caches will make your site slower, especially the Configuration Cache since it will rebuild all the configuration XMLs on every page load.

Use the profiler you have screenshot, go down the list and check which last element takes a lot of time to load and you will have your answer.

As a first step you can disable all your modules (just move all the .xml files in app/etc/modules to a different directory is sufficient), and check if it's still slow. If it is, then you can rule out your modules and it could potentially be an environment problem (aka your machine, or the way it's been set up)

Answer 2

based on the profiler output you provided here are possible performance issues:

• session start takes too long. this has been covered here Long Running Admin Page Requests Blocking Other Requests. try switching session storage to database and see how it affects site speed.
• inspect header.phtml, top.phtml, 1column.phtml, place Varien_Profiler::start Varien_Profiler::stop here and there to identify the slowest part.
• check if you have mysql query cache enabled. by default modern mysql servers has it disabled. enable it.
• I see EAV_COLLECTION_LOAD_ENT called 16 times. it is called when for example you load product collection. what collections you are loading? do you really need to load it 16 times? try to inspect templates and lower than number.