>It felt very slow in comparison to apt
This is partly true, and partly not.
DNF always updates the local copy of the metadata, so it's more like "apt update && apt upgrade" than just "apt upgrade". I don't recall if Ubuntu has a background task for this, but that might be one reason it's "faster".
DNF also has more metadata to download, and the default parallelism is not very high. If you increase the setting, it gets a lot faster.
And also, DNF records the package update history, so that the origin of every package on the system (whether it was requested installed by a user, or indirectly as a dependency, whether it came from a repo or was side-installed) is auditable. Transactions are recorded and can be viewed and rolled back afterwards. And it uses a more rigorous SAT-solver based approach to dependency solving than apt uses. So it's likely doing more actual work rather than being slower at doing the same thing. Those features can be quite useful.
