I have the following specs for a dedicated server where I have magento installed:
Site is still slow, I have paid somebody to tweak it too couple of days ago and still slow, as if there has been no change.
What is wrong?
There is varnish, nginx, a full page cache extension and cache warmer amongst other optimizations to the server but no change!
There exists Cloudfare CDN, a minify JS, CSS, HTML etc. extension but as my site is customized, I have been warned not to turn it on as it will break my store? Can someone clarify this?
Would appreciate any assistance to the above as have spent a lot of money on optimisation but no luck last few months to speed up the site to it's max potential
you just have to find your slow part, is it mysql or php
if you paid someone to optimize your server - did you get any reports ? what exactly was slow and what was optimized???
install profiler to find out.
It may be possible that your optimization are not done properly or not suited for the store.
Another possibility that I can think of is you may be physically very far away from the server? The distance and thus high latency may be the cause of the slowness if you've ruled out everything else. If this is the case, you may want to get a server which is nearer to you or your target audience.
The usual list: store count; product count; extension count; who implemented hosting; who designed the theme.
The simple answer is usually hosting, the problem is most think they are/have the best, most don't.
Minify can break sites, you need to perform a full regression test on a copy of the site before launching it.
Have you done any profiling on the site to find where the bottleneck is? The server hardware is definitely fast enough so most likely there is a problem within the code. If you paid someone to optimize it they should have provided you with a report of what was fixed and where the problem lies.
Also you can't always blame the server. Many times have we troubleshooted client sites only to find out that there is some outgoing Curl request to an external server that is either responding slowly or timing out. No server upgrade would ever fix this. The first step is to use a code profiler or the built-in Magento profiler to locate the bottleneck. Some times it can also help to trace the PHP process on the server side, but this is beyond what can be covered on these forums.
How many products do you have in your store? Do you have any "heavy extension"?
First of all cache != performance. You need to dive deeper and perform Time to First Byte audit.
Magento has a thing called profiler. Turn it on and analyze its trace. Here follow this tutorial https://www.goivvy.com/blog/magento-ttfb-optimization .
A dirty trick would be to do 3rd-party extension audit. In most case a poorly-written plugin can slow down Magento site. Get a list of all custom extensions installed on your Magento and disable them one by one. See if that improves speed.
There are other 20 field proven optimization steps that you could find here - https://www.goivvy.com/blog/magento-speed-boost .