UPGRADE 1.5 TO 1.5.2.1 .FIRST BYTE VERY LOW

Hi

IF somebody can help it will be really appreciate.

Our website www.dzignart.com was before yesterday on opencart 1.5.1
The First Byte from webpagetest was at 0.6sec and the total 3.3sec

Since I did the update from opencart 1.5.1 to 1.5.2.1 my first byte is 1.5sec, so very very long.
http://www.webpagetest.org/result/120504_HV_47J42/

We have change nothing since yesterday and
-our database is still with the same number of products (2500 products),
-I have just 4 vqmod that load,
- use default theme with color modificaiton
delete count of product per category
delete log error
our apache server is setup with deflate module (gzip compression : txt, image...)

Do you have any idea of what i need to change. Database optimisation, Cache????...

Upgrade from 1.5.1 to 1.5.2.1 should increase my speed, not become very slow. I am sure that it s not my hosting, because we have full dedicated servers and everything was fine yesterday morning

Thanks in advance

An

If it's first byte, it's down to your hosting and we can't help much.

Hi MarketInSG
Thank you for your help
I am sure that it s not from my hosting, because on the same dedicated server, I have several domain with opencart 1.4.9 or 1.5.1 and the first byte is 0.6s and on the other domain where I did the upgrade from 1.4.9 to 1.5.1 to 1.5.2 the first byte is 1.5s
So I think the hosting is fine.
Between 1.5.1 and 1.5.2, do you know if the configuration of appache need to be different ?

Tried everything but still have a very long first byte

Tks in advance
An

Find my solution in 5minutes with this module
http://www.opencart.com/index.php?route ... alp&page=1
SERIOUSLY, THE BEST MODULE THAT YOU CAN BUY. IT S A NO BRAINER
First byte before of 2.8sec, after 0.38 and a google page speed of 97.
Load Time before, 7.565s after 3.266s

Installation of the module, really simple : take 5 minutes...
you can compare
http://www.webpagetest.org/result/120505_F7_47SMB/
http://www.webpagetest.org/result/120506_WR_483AV/