Is server compression making my site seem sluggish?

[trevordixon]

I'm rebuilding a site that was originally coded in C and runs extremely quickly. Now I'm trying to optimize the new PHP/MySQL site and pages aren't appearing fast enough in the browser. The old pages seem to appear in Firefox 3 to 5 seconds quicker than the new pages do.

The old pages appear much more quickly than my new PHP pages, but I don't think it's because of the PHP code itself. I ran the Microsoft Web Application stress tool on the old site and on my new site, and the average response time for my new pages was approximately .7 seconds. The old page's response time was about .3 seconds. A half a second difference in server response time shouldn't make my site seem that sluggish, should it?

It also said that the total download amount for my new pages was like 7kb even though it's closer to 35kb, but the download size for the old page was 34kb--the actual size of the page. I think that means the new site is getting compressed before served (the old site is running on a shared host and the old site is on a dedicated server that a friend of mine maintains).

Is it possible that the old site isn't getting compressed first and thus it can start being shown before it's entirely downloaded while the compressed pages have to be downloaded completely then decompressed before the visitor can see anything in the browser?

Thanks in advance for your wisdom and advice,
Trevor

[edited by: coopster at 2:12 am (utc) on July 4, 2007]
[edit reason] no urls please TOS [webmasterworld.com] [/edit]

[coopster]

Have you checked the return headers to see if the pages are indeed being returned compressed?

[vincevincevince]

Your suspicions are almost certainly correct. Another thing to watch for is that some layouts which the renderer cannot show until the html is all loaded will be slower - but if the HTML result from both scripts is the same then there shouldn't be a problem.

Finally - you are comparing performance on a shared server to performance on a dedicated server. Are you sure the shared server isn't under spec or over loaded?