Why does my laptop run considerably slower when it gets below 85% free space?

Sure, my computer’s old, but my 80GB hard-drive is less than a year old. Yet, this is a problem that I had even when I had hard-drive with only 40GBs. Once it gets below about 85% free space, it starts getting a little slower. Why is that? What’s the point in having the space if you can’t fill it up. Is there something I can do, other than defrag and system cleanup, to get better use of the space?

My comp:

Dell Inspiron 8200
Windows XP
80gb hitachi harddrive
1gb RAM

That’s got not much to do with specs.

When you open a file (and that can be lots of things, from a Word document to your last saved game), Windows makes a copy - you’re working on the copy, not on the original. Windows also has a series of “index files” which it uses to keep track of which files are stored where; a large file is stowed in several different directions. Let’s say that a file takes 30 spaces and your HD is pretty clean. When you open it, the system puts the working copy in spaces “40 to 69”.
Let’s say you open the same file but the system doesn’t have a large enough bunch of spaces handy. Then it gets stowed on spaces “40, 68, 90 through 102, 110 through 113…” See how the index file gets a lot bigger? Not only does it take more space, but finding all those bits and putting them together so you can use them takes longer.

If you’re like many of my customers who complain about “my computer is very slow when I use the accounting program,” you’ll have open:
two instances of Adobe,
twelve documents in Word,
six Excel files,
three copies of Paint,
and six instances of the accounting program (five of which say “read only”).

Each of those is more copies, which are scattered all over the place, and composing them is kind of hard for the poor thing to keep track of.

What defrag does is give your index more ease of work. System cleanup (which should always be used before defrag) gets rid of trash files which you do not need (for example temporary files left behind when a program crashed).

Could be that the paging file (disk space used by Windows when it runs out of RAM) is getting fragmented. You can prevent this by using a fixed-size paging file. See Tip no. 5 on this page:

Would this have a knock on effect on DVD performance?

I’ve moddy coddled my laptop since buying it last year and just recently (when I noticed my hard drive filling up to a few GB free out of 100) movies have replayed very jerkily and DVDs can only be written at a low speed. Before I consider sending it off for a warranty repair, would freeing up all this space help?

It’s also just an unavoidable fact, as far as I understand it, that your disk should theoretically perform slower as it gets filled up (there’s no magical threshold at which it goes from fast to slow, it would just gradually gets more sluggish). This is basically because since the HD platter always spins at the same speed, the outer tracks will give you more throughput than the inner tracks. Your computer will use the outer tracks first and they will give you the zippiest performance. As you fill up the drive you are accessing the inner tracks, which will be slower.

I’ve read that because of this, some people suggest that you should try to install your most important applications first, so that they get the prime real estate on the platter. This could mean uninstalling all the demo software that comes with a new computer. I don’t know how much this actually makes a difference, especially with today’s monster drives.

However, this probably shouldn’t affect DVD performance. I suppose it is possible that in playing the DVD, the CPU needs to do a lot of decoding and if the system has insufficient memory, it may be forced to go to the pagefile. In which case your HD does get involved and if your pagefile is scattered around or ended up on the slower inner tracks, then yeah, maybe.

Yes, it affects all performance.

Always try:
if that doesn’t work,
-switch off completely,
-give it at least 15 minutes,
-start up and don’t start opening stuff until it’s really really finished
if that doesn’t work,

  • system cleanup,
  • take a good hard look at your installed programs. Do you need to keep that one you haven’t used in 6 months? If you need it again, will you be able to reinstall it without a lot of pain? Take it off. Some programs claim to take very little space but actually are enormous hogs (the Sims is one of the most outrageous examples for this).
  • defrag.