[vonseel]

> For that sales report, that runs once a month, and takes 10 minutes, but could likely easily be optimised to run in 2 minutes, the trade off is less obvious. Keeping the report easy-to-maintain is a valuable long-term benefit.

I did this before, actually, and it was worth it for the client wondering why their report took 30 minutes to generate. The particular instance I'm thinking of was a poorly written SQL proc, which I improved upon to reduce the report generating time down to <10 seconds, and it took a couple of days of work to rewrite the original developers work. If I were a better SQL developer that would have been much less.

Another case of optimization required much less effort, I literally went in and switched the library used to generate a PDF from HTML and improved performance 100x. I don't remember the original tool used, but wkhtmltopdf was probably the better performing one.