I would separate snap and apt as before, meaning do not install snaps through apt.
Snaps are fine to run software as they ship their dependencies, and that add a lot of value. For example, it makes a discontinued package really easy to keep running: just ship all its old dependencies into it and harden the sandbox to avoid conflicts and security risks.
But at the same time their sandboxing might get in the way a lot. It sometimes affects the integration with the system software or existing dependencies; e.g., a Thunderbird snap may not find the system's GnuPG.
In terms of performance, they run exactly as fast as .deb software; the only difference is the time it takes for the software to boot, as they are compressed squashfs volumes that are mounted and extracted on the spot