I would start with the usual suspects.
- How are you using DBI? Are you following the best practices as outlined in its POD?
- Are you creating and destroying lots and lots of nested datastructures? This can be expensive.
- Are you using mod_perl? If you are, are you taking advantage of its more advanced features?
- Is your schema normalized? Do you have the correct indices on it?
- Is your server the correct size for your application? If you have your database on the same machine as your webserver and it's a 1-CPU machine with 1GHz and 1 10k RPM harddrive ... there's not that much improvement that can come from improving the code. You're going to be IO-bound no matter what way you cut it. (Adding a CPU, interestingly, can improve that. Adding striped disks is better. Moving the database to another machine is best.)
I would suspect that if you examined the above items, you would get a 50% or higher speed improvement.
An example - I came on board at my current company to speed up some reports. The first thing I looked at was the performance of the SQL. By reorganizing the schema, I took the time spent in the database from 243 seconds to 3 seconds. Not a single other thing changed.
Then, I looked at the presentation layer. Converting from Oracle's Application Server to mod_perl + CGI::Application + PDF::Template took the report presentation from 30 to 2 seconds.
So, just by examining the architecture, the reports went from just under 5 minutes to around 5 seconds.
After that, I went ahead and ticked off every item in the checklist I listed above. The webapp now does about 100x what it used to do in about a tenth of the time.
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We are the carpenters and bricklayers of the Information Age.
Then there are Damian modules.... *sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon. - flyingmoose
I shouldn't have to say this, but any code, unless otherwise stated, is untested
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