My opinion is that there is no low threshold for RAM use. If you can go down from 200kB to 100kB, that's still a win, even in a 32GB machine.
The reasons:
- Cache. RAM may be >8GB but the CPU L1 cache is just 64kB. And L1 cache is about 100 times faster than RAM. From my experience, proper cache management is by far the most important low level optimization, and most of it can be archived by just using less RAM.
- What are you doing with all that RAM? 250MB in absolute terms is huge. The entire Harry Potter series is around 5MB uncompressed. For that size you can also have a 1080p fullscreen RGB image, uncompressed. What it means is that unless you are working with large datasets, these 250MB represent a huge amount of stuff you don't control. Lots of moving parts with potential performance bottlenecks, security issues, etc...
- Every byte your app is using is one less byte for your system caches. Wasting RAM makes your whole system go slower.
- Finally, an ethical argument. Your chat app will run continuously on millions of PCs. On that PC are libraries, kernel code and frameworks where people worked hard squeezing every bit of performance they could. Saving energy and making your apps run to their full potential. For me, a background app made by a company the size of Slack have a duty to be as light as possible, as not to interfere with the actual work people are doing on their machine.