003r + Command8 + 2011 iMac

[zv yoda]

Hi folks,
My system has been very stable for years, so I haven't had any real reason to frequent these parts for quite a while. It's still mostly stable, but I'm getting occasional crashes and notice that some VSTs e.g. Superior Drummer 3, Izotope Iris and Analog Lab 4 take a long time to load up (and are crashing more frequently these days).

My setup

• Pro Tools 2018.12.0
• Mid 2011 21.5" iMac running OSX 10.13.6 24Gb RAM
• Digi 003 rack + Command8

I use the iMac system drive for OSX and not much else.

I have a 750Gb 7200rpm Maxtor One Touch 4 Firewire external drive partitioned into a PT session drive + sample library. I have a separate USB external drive as backup (no probs there)

My problem
The setup has served me well over the years and I am very reluctant to start upgrading for the sake of it. That said, I am seeing some crashes, and my external drive is almost at capacity. So, what's my best option to shore up the system for another few years?

The simplest solution would be replacing the 7200rpm external drive with an SSD in the same Maxtor enclosure (not even sure if that's possible). Are there other options I haven't though of? I've looked to buy external drives that have FW+ SSD. There don't seem to be any (not surprising since FW is very old tech at this stage).

The extreme solution is to upgrade my hardware and software. Whatever about the cost, I'm happy with my setup and have no appetite to re-ignite my GAS addiction. Plus, I'd have to seriously consider switching to PC, since Macs are no longer user upgradable.

I'd really like to give my existing system a much-needed shot in the arm.

Any thoughts appreciated!