Hard to compare the two programs over a week of uptime. ST memory usage does get larger as caches get filled over time, but I've had uptimes of months without issue. I'd expect similar results from other editors.
Do you have a specific memory issue where it keeps using more over time?
General issue, have observed it on multiple systems. On a long enough timescale, will grow to farcical amounts of memory usage.
Unfortunately, while this is something I've observed through major point releases and on different platforms, there have always been some plugins in use.
UnUnfortunately not enough commonality in configuration or hours in the day to track down if this would happen on a totally clean install...
I'm sure your roadmap is quite extensive, but it would be great if sublime itself could graph or warn when memory usage increased by some specified percentage, or if any particular plugin spikes resource usage.
Plugins are a frequent culprit of issues like this. Depending on how you're tracking memory usage you may already be able to at least narrow down the culprit by looking at which process is using too much; plugins run on a separate process and may launch additional processes from there.
Unfortunately tracking individual plugin memory usage is not possible without invasive (and slow) tracing. If the plugins are causing big memory usage in the main process it can be hard to nail down due to that state being shared between all plugins.
Do you have a specific memory issue where it keeps using more over time?