It's not that vichan and tinyboard are bad, they are just not for scalable imageboards. If they reach a certain threshold then the software will start having deadlocking problems due to shitty code. It's completely fine for smaller imageboard. I even go on one that gets 1000 posts a day and it's never been a problem. There's absolutely no need to worry about the software. The only thing needed with it is to make sure you can maintain it occasionally, but as is the case with every imageboard software, even those not supported anymore.
The main problem I feel that vichan has is that it's built so much with providing a "4chan experience" that the code is fucking awful and instead of fixing any of the numerous flaws that the software has, they just integrated new features and built them around the code. It's absolutely terrible for customization (MP3 embeds, board specific CSS, and a whole platitude of other things I could probably list, but I guarantee nobody is interested in me drone on about the many issues the software has.
That being said though, for a basic and small imageboard, ranging anywhere from 0 to maybe 5000 users, it does its job great and with minimal issues, which isn't something you can say about any of the other aging open source imageboard softwares. There are still sites using Kusaba X of all things, so these problems can be fixed, it's just a matter of if it is really worth the time (which it isn't. Just take a class in perl and work on making Wakaba a bit better if you're truly interested. All other open source alternatives are crap.)