technology

Are there any alternatives? Is Brave any good?

No (well, sort of, but not really). Brave Software suffers from the same problem as Mozilla in terms of flailing desperately for monetization strategies, but Brave is downstream of Chrome (via Chromium), and ultimately bound for a similar fate unless they magically find the resources to fork and develop their own independent browser engine. They likely can hold on to Manifest 2.0 for some time, but at the cost of accumulating technical debt. There is also LibreWolf (my personal recommendation), which is downstream of Firefox, removing most of the weird shit Mozilla does to try to create an alternate revenue streams to the noose Google provides in the form of default search sponsorship. The only other alternatives worth consideration are Safari (Apple exclusive, no ad blocking, boo), and downstream browsers based on WebKit. These are getting pretty obscure though. Most have transitioned to Blink (Chromium) via QtWebEngine or their own means. Only a handful of noteworthy examples (like ~~qutebrowser~~ and Gnome Web) remain.

It eats up a ludicrous amounts of RAM, which I wasn't expecting since it's one of the main things people make fun of chrome for

Modern websites get more and more bloated, both computationally, and in terms of assets. Assets like images, scripts, stylesheets, audio / video, etc. need to be stored somewhere. These can either go in memory (fast, but consumes memory), onto your disk (at least an order of magnitude slower than memory), or be re-downloaded every single time they're needed ("dogshit" slow, and will destroy your quota on metered connections like mobile carriers).

Using RAM isn't inherently bad. It is the best place to cache data if the space is not needed for other purposes, and this cache can be purged very quickly. RAM that isn't being used does nothing for you, and caching things on the disk (HDD or SSD) causes wear over time, while caching things in DRAM does not. If it is not causing performance issues for other applications on the machine, it is not a problem.

The setting isn't exposed directly, but can be manipulated in about:config. Specifically browser.cache.memory.capacity. There are other settings under browser.cache.* regarding disk usage. By default (-1), they are set dynamically according to the amount of RAM and disk resources available on the system.

The whole point of caching though is to increase speed. Grabbing something directly from RAM instead of getting it over the wire is supposed to be fast. If it is caching an absurd amount of data and still going slow, something is wrong.

It crashes constantly

There has got to be something else fundamentally screwy going on with this computer. I don't mean to come across as a fanboy (because I am actually quite pessimistic about the direction the web is taking, and Mozilla's 'stewardship' of the only viable alternative to Google), but Firefox has always been among the most stable applications I have ever used. Occasionally, some websites don't work correctly, but things like crashes have been incredibly rare in my experience.

Web browsers are among the most valuable targets for zero-day exploits and malware. By necessity, they are among the most field-tested and hardened pieces of software around. This is one part of the reason why there are so few alternatives available. If your browser is regularly crashing, this is A: very atypical, and B: a cause for concern, as crashes often indicate a potentially exploitable programming / configuration error.