It really depends on the errors that you are getting.
For example if you are getting a lot of Exec processor errors it could be that Splunk can't run a script because of permission issues. That probably won't affect performance that much.
However, if you see a lot of Regexor processor errors it probably means that you have a lot of slow or inefficient regexes. Or maybe you've got events with more than 256 lines and based on your configuration, you are truncating events without times stamps and that will slow splunk down. If you up the event size in this case, it would help those errors.
If you see Aggregator process, Date processor verbose then those are all related to props.conf and you could be having issues with line breaking, line merging or time zone issues which could certainly affect performance.
There are a lot of variables and it might be worth a call into support or if you think it's the right time to clean up your environment you can bring in our Professional Services team to do some work and show you what to look for in the future while the fix the existing issues.
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