Programs/apps/games slowing over time?

Question

I'm trying to find the reasoning to explain why this happens, but I'm not well-versed enough in memory, RAM, etc. to accurately explain it well enough.

So can someone give me the reasoning as to why programs running for a while get sluggish over time?

For example if I open Photoshop and edit files for 20 minutes, and then leave Photoshop open for let's say 24 hours, and come back and edit more files for 20 minutes again, Photoshop will be more sluggish than when it was originally opened. Why does this happen?

Note: I'm saying this scenario in more of an overall sense as to why computers due this, so not necessarily memory leaks or not having enough RAM. If I were to go buy a brand new computer and use Outlook or something for 10 minutes, and then leave Outlook open for a day and use it again, it's not going to be as snappy and responsive as it originally was when first opened. Hopefully that is a good example to explain the general computer issue I'm talking about!

Answer 1

Area of memory that are not used for some time, will be swapped out by Windows to the page-file, so as to maximize useful RAM space. When re-used, the memory pages will be read on-demand.

This means that when started, all of outlook.exe is read into memory and is immediately available for execution after the short wait that we all find acceptable when a program starts.

But when you come back after a long absence, the program will be on disk, but memory will be read in piece-by-piece, not all-at-once, so this will be slower in execution. However, after using the program for some time, response should improve back to what it was before, after all the code and data that you use repeatedly will already be found in memory.

If you leave again, this cycle will repeat itself.