New droplet or droplet upgrade?

This really is a question of preference really and what the needs of your client(s) are. With running a single droplet and all the sites in one regardless if you resize it up you are running into a ceiling in regards to performance at some point.

You may or may not see it, however if you do, say one of the sites all of a sudden begins to get tons of traffic and consumes allot of the single droplets resources, the other site(s) may also see a decline in performance.

Using two droplets would spread the load between both and only have some sites effected in the above scenario.

Another solution is to perhaps look into a distributed setup making use of something like Docker

https://www.digitalocean.com/community/tutorials/5-common-server-setups-for-your-web-application

Thank you for the response, sir… I had considered that distributed setup as well, but hadn’t yet done the research into the work I’d have to put into it. It sounds like it might be a decision best saved for when I see what’s actually causing the slowdown (i.e. bandwidth, RAM, or something else) - it’s looking like right now the LIMFAC is going to be memory - I have CPU and bandwidth to spare, but as you pointed out that could change at any time. Thank you for the link - I’m going to add that sort of solution as a possible as well.