How to improve UI performance for legacy applications

Recently I came across a scenario where customer reported that he installed application on new server with all software upgraded to their latest versions (including browsers) and suddenly he saw UI taking 20 seconds to load, and sometimes gave a script timeout error. Application was developed using GWT. After trying out many things, starting the browsers in safe mode helped and the UI load time reduced from 20 to 2-3 seconds.

Below are some of the steps that helped us speed up the thing.  In case you have any other ideas/comments, please post in the comment section.

1. Start browser in safe mode and see if it helps

Mozilla Firefox:

Click the menu , click help and select Restart with Add-ons Disabled.... Firefox will start up with the Firefox Safe Mode dialog.

Note: You can also start Firefox in Safe Mode by holding down the shift key while starting Firefox.



You now have two options:

• Clicking the Start in Safe Mode button will temporarily disable your extensions and themes, turn off hardware acceleration and reset toolbar and button customizations. When you leave Safe Mode and start Firefox up normally, your extensions, themes, and settings will return to the state they were in before you entered Safe Mode.
• Clicking the Reset Firefox button will restore Firefox to its factory default state while saving your essential information.

Chrome:
Google Chrome doesn't have this feature of opening in safe mode, but you can open an incognito window to temporarily disable extensions.

Internet Explorer:

• Click on the Start button.
• Type "internet explorer" into the search box.
• Choose Internet Explorer (No Add-ons) from the Programs list.

Please disable Scripting too; this may lead to crash of Internet explorer:

Steps to disable:

• Open the Tools menu (Alt and T)
• Select the Internet Options item (O key).
• Go to Advanced tab, Disable script debugging (Internet Explorer), Disable script debugging (Other) and Display a notification about every script error
• Apply the Changes.

2. Reset browser profile in case of firefox

In the Profile Manager, select the profile to remove, and click Delete Profile.

Confirm that you wish to delete the profile:

• Don't Delete Files removes the profile from the Profile Manager yet retains the profile data files on your computer in the storage folder, so that your information is not lost. "Don't Delete Files" is the preferred option because it saves the old profile's folder and allows you to recover the files to a new profile.
• Delete Files removes the profile and its files, including the profile bookmarks, settings, passwords, etc.

3. Enable pipelining and number of pipelined request in mozilla by setting properties in about:config. This may also help to improve performance in some cases.

4. There is a tool, Microsoft Fixit which checks for any issues with IE. Use it to clear the profile data and restart the IE browser. It may help to improve the UI performance.

Above are some of the things that helped in our case.  

Feel free to share your ideas below in the comment section.