One of the worst nightmare for any Joomla webmaster is this very problem. Log in to your admin control panel and the world seems to be stopped.
Problem become worst to understand when: -
The internet speed is very fast.
The front end of the website is opening fast.
All the other Joomla website are opening fast.
In local server the admin backend is opening fast.
Then what causes the Admin Backend of our Joomla in server extremely slow - Are you totally confused ?
This root of all evils is not Joomla. To the best of my knowledge this is not the problem or bugs of Joomla. The concepts of the problem lies with the type of server , server space and hosting plan in which the Joomla website is being hosted.
Firstly, The Joomla (Worlds best content management system works best in Linux Server). So if the Joomla if being hosted in any windows server then there is an higher chance of the Joomla Admin Panel to open extremely slow. This is because windows server don't supports many software and components like apache web server etc. While in offline mode in windows - in local sever it will work fine as a server software like ''WAMP Server 2.0' is being installed.
Secondly, if in single IP (Internet Protocol) many website is being hosted then there is probably a greater change of facing the above problem.
Thirdly, if the My SQL database is being shared for many website with single IP (Internet Protocol) these type of problem may appear.
Fourthly, the problem also may appear if very low server space is being allotted to the Joomla website.
Check Point : To avoid the problem.
The website is not hosted in windows sever.
Many website are not hosted with same IP. Its better if you have a dedicated IP
Mysql database is not shared by many website under same IP.
The server space allotted to the website is not very low. Because a new Joomla installation it self takes 20 -30 mb of space. And if total sever space allotted to the Joomla website is just 35 - 40 mb then obviously the admin panel will open slow.
Note : This problem happened with our juniors staff while he was developing a website for a local school using Joomla which was hosted in windows server. When we transferred the website to Linux server the problem was solved.