Website loading speed - slow html loading

Who can help me.

I have a webshop running on magento 1.6.2.0. A VPS server with apache 2. I have APC and memcache, varnish cache and fooman speedster running.

The main page has acceptabel loading times ... But when i go to a category page it takes a lot longer ...

But the must waiting time is consumened by waiting on the html page to load ... See the screenshot: enter image description here

The loading time is now around 2-5 seconds, but when its busy on the site it can run up to 10-15 seconds ... so much to slow ...

When i take alook with firebug i see the most time of the loadingtime is waiting ...

So my question is, how can i reduce this?

Solution

benmarks and josh pennington are on the right lines, ingnore the others who are telling you to cut down the number of requests for now as the extra requests are a distraction right now.

The problem is the HTML page takes too long to generate, and under load this gets worse.

Often this is down to the DB being under too much load, either through poorly optimised queries or not having enough memory.

You need to establish what queries are executed on that page, and what their performance profile is e.g. memory, IO, CPU usage.

What size VPS do you have? You also have to consider whether it's got enough memory.

Also are you running Apache? If so how many workers does it have. What may be happening is that at busy times there manpy not be enough workers and they may not be able to process quickly enough so at busy times some requests are queuing whil waiting for a worker to become available.