

Rubbing alcohol and a microfiber cloth.
Also, I feel like I’ve had good luck with k3b, though mainly for CDs.
As for drives, as others have said, USB ones tend to be janky; go for an internal. I like my LG WH16NS40 Blu-Ray drive.
If it’s a desktop, it should be easy to hook up with SATA, though if you have a newer case, you might need to dangle a cable out the side like I do.
If you have a laptop, though, you’ll probably need a USB adapter, though there might be a hack using an M.2 slot to hook up an SATA PCI-E card.
May I ask what your config was, such as distro, packaging format, and extensions were used? Also, what hardware?
Additionally, what issues specifically were you experiencing specifically? Were sites just loading slowly?
I ask because I’ve used recent versions Firefox on decently old hardware with 4 GB of RAM and 2 cores and had almost no problems. Everything rendered correctly and in a reasonable amount of time. I’d be curious to know why that isn’t happening for you.