How do I impove 1.5.4 version's loading speed on my Windows PC?

Hello! All teachers. I am a new user with zencart, I have met a troubled with using this software in recent days.I have installed 1.5.4 version on my computer, and optimized it according to normal method. But it is still very slow on loading homepage, it was more than two minutes, even could not download whole homepage. I have searched answer in here, some friends seemed to say that relate to php version. my php environment is Apache/2.2.22 (Win32), PHP/5.4.6, mysql/5.0.10, it is below v1.5.4's demand. but this demand seem not to be necessary condition, so it can working in my php environment. But I want to know whether this lower php version cause loading homepage slowly. When I install superior php environment, can it impove loading speed? How am I able to efficiently impove loading speed? thanks answer!

Welcome to the Zen Cart community!

You've told us some, but not all, of your current configuration. The only time that I've seen Zen Cart v1.5.4 load very slowly is when the cart's server configuration has issues.

You said "I have installed 1.5.4 version on my computer". Is this your local computer, where you are using XAMPP or similar for the hosting, or is your cart hosted by a webhost?

Thank lat9 teacher's point! Zen Cart v1.5.4 is installed at my local computer, but not on webhost. Server is configured by myself, and isn't used like XAMPP or similar integrated software. I have modified php.ini's part parameter today, increased max_execution_time and memory_limit's numerical value. Now whole homepage can be downloaded, but speed doesn't be improved observably. I looked for relevant materials in internet, found Zend Opcache had been integrated into PHP5.5, so PHP5.5 should much more faster than PHP4, hence superior php version should more help to improving v1.5.4's speed.
Today I have installed CSS JS Loader on v1.5.4, find it's speed is obvious improved, it also is an important harvest. Now I am trying other methods to improving v1.5.4's speed, and hope to obtaining more help.

The CSS/JS Loader, as you've found, can be a big help in a page's load-speed.

It's going to be very difficult to help you diagnose why your site's loading so slowly, since there's nothing to use as a comparable benchmark. I'm hoping that some of the community members that are more knowledgeable about various server setups can provide you some guidance.

I need to alter a mistake that I have said before, it is that PHP5.5 should much more faster than PHP5.4(my PHP version is 5.4.6).

Hi
I do use kubuntu machine to development work daily with php/myslq server installed (used xamp in old days) and didnt noticed any performance issues with 1.5.4 so it has to be related with your server configuration (assuming we are talking about clear vanilla zen installation).
Once You will sort out server config try some IDE like neatbeans with kcachegrid installed to analyse program route and look for some bootlenecks.

Thank store-support's advices, those are some very good ideas! Reason is founded now, it is certainly that I used lower PHP version. after I install WampServer 2.5, loading speed is great improved.

Now I find a new method, it can solve speed problem what I said before. It need to alter httpd.conf's configuration, ServerName value is localhost, look like "ServerName localhost". It has greatly improved my website's loading speed.
I have configured a new php environment on my windows pc recently, it was composed by Apache/2.4(VC11), PHP/5.5.32, mysql/5.6.29. but it has generated two problems when zencart was installed, one is that it was showed "PHP cURL Support = OFF", another is "Apache .htaccess Support = Could not test - no CURL support". I couldn't find solution, and hope friend's help.

but it has generated two problems when zencart was installed, one is that it was showed "PHP cURL Support = OFF", another is "Apache .htaccess Support = Could not test - no CURL support".
Both look to be rooted in curl support

One needs to recompile the php with curl support

Thank kobra's point! It is very good idea, I have solved those problems now.