The workaround tells you exactly how to add the preference in about:config. You may have missed it, so here it is in bold type:
Browse to about:config (clear the Location Bar and type: about:config)
Scroll down and look for browser.cache.memory.capacity
It shouldn't be there, but if it IS:
Select: "Modify" and change to 1024
Skip the next step
The above instructions are only IF the script is listed. Below is how to add the script as NEW:
Right click anywhere on the page
Type in: browser.cache.memory.capacity
For INTEGER VALUE: Type in 1024
Restart Netscape (or Mozilla)
If you have a large amount of RAM I would suggest using 1024
for the Integer Value, rather than 2048, or 4096. If no joy, then increase to 2048.
The Resource Leak Web page: http://home.att.net/~cherokee67/ns71resrcleak.html
lists a Show 'N Tell on adding or editing Preferences in about:config:
Re: adding the memCache setting to the user.js, I disagree with Fulvio, for these reasons:
Setting memory cache by adding the script in the user.js file locks out making permanent changes via the UI (user interface) or, in about:config. These settings are profile spefic - not global - as it is if added to a *.js file.
In Netscape 7, If you set memory.cache.capacity in the user.js file you can change it via the UI: Edit | Preferences | Advanced | Cache. However, the user.js file will override every time you restart 7. The setting will be retained for the session, but not from a re-start. In effect this will preclude any changes you make in about:config from becoming a permanent change, which normally takes effect AND is written to the prefs.js on exit.
The resource leak could very well be the reason for the slowdown, however, if resetting the memCache value doesn't solve the issue, then you will need to look elsewhere.
Edited for a more precise workaround guideline - per member request
UserAgent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.5b) Gecko/20030827