What the Heck is a "Browser Cache"?
Tech Tips Volume 2004 No. 13
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Note: This Tech Tip is for Internet Explorer 5.0 and above. If your version is older, it's obsolete and has security vulnerabilities not present in newer versions. Upgrade to version 6 now for free at:
http://www.microsoft.com/windows/ie/downloads/critical/ie6sp1/default.asp
About browser caching
When you surf the net, your browser loads page images, sounds, text and more into
a special area of your disk called your "cache" (pronounced "cash").
Cached items are stored (along with cookies) in your Temporary Internet Files folder.
The advantage of caching: when you revisit a page, the browser can reload it from your
disk, which is much faster than downloading it again. Cached content also allows you
to browse "off line", which is handy if you pay for connect time or if
surfing ties up your only phone line.
But cache sizes that are too large have a downside: you can end up wasting disk space.
Also, an oversized cache can actually slow down your browser,
and even hamper the performance of other applications. By default, your cache size is
probably set to 10 or 20% of your total drive space, which is much
larger than most users need, and much bigger than most experts recommend.
How big should the cache be?
Most experts recommend a cache size between 20 and 40MB, though some recommend a size as
small as 5MB or as large as 80MB. Here are some factors to consider in determining
what's right for you:
- If you have lots of disk space, you might err on the side of larger. If space
is at a premium, go smaller.
- If you surf the net infrequently, or if when you surf you rarely revisit a
site, cached pages won't be of much use to you, so choose a smaller cache.
- If, on the other hand, you surf frequently, revisit pages often, or browse
off-line a lot, caching is useful. So choose a larger cache.
Changing cache size
Most likely, based on the above, you will want to reduce the size of your cache.
So the first step is to empty it: Go to Tools | Internet
Options | General tab, and in the Temporary Internet Files section, click the
"Delete Files" button. (You should do this periodically as a matter of
course.)
Next, click the "Settings" button right next to the "Delete Files" button you
used in step 1. Reset the cache to the desired size by using the up/down
arrows or dragging the slider. It's very important to delete your temporary
files before you shrink your cache, or you could end up with an unfortunate
condition called a "cache overflow" (see below).
Controlling cache refresh
In the same window that specifies cache size are choices for when your browser refreshes (i.e., re-downloads) cached items. For most users, the settings "Every time you start Internet Explorer" or "Automatically" are fine. (You can always use the refresh button on your browser toolbar to force a refresh of the current page.)
A note on cache overflows
There are circumstances (some fairly common) under which Internet Explorer "loses track" of some items in the cache, and as a result, builds a bigger cache than what you specified. This can cause all kinds of erratic behavior, and not just in your browser. We'll deal with this in next week's Tip!
Copyright 2003-2005 by Shulman Clark Associates, LLC. All rights reserved.
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