From my experience, errors like these aren't necessarily the cause of your noted performance issues - they may be a symptom. If the system is busy processing a ton of information (e.g. there's a lot of activity going on, a large pdm_load is happening, archive & purge is running, etc.), it may slow down and miss its' intended fire times for scheduled events. I've also seen this kind of message occur when SLAs are configured and a ticket with a large number of children is closed - the animator suddenly has hundreds (or more) events to process, and can't handle them all on time.
If you're seeing "missed 1 firings" frequently, but don't see the same event get missed 2 or more times, it might indicate that you're having the server do too much work with too few resources - it's still processing everything, just at a bit of a delay. For that situation, double-check that you meet or exceed the minimum hardware and software requirements, and consider increasing the number of servers in your environment if you have a lot of activity on a small number of servers. If you're seeing the same events miss their fire time multiple times each, then that could indicate that the animator isn't processing fast enough to keep up with demand - setting up an animator-specific domsrvr as Paul noted earlier may help here (though again, make sure your server has enough resources to do this).
Since this is likely more of a symptom of a performance issue than a cause, I'd also recommend reviewing some of our troubleshooting suggestions for performance issues, linked below.
How to Identify Performance Problems in CA SDM