You can use the round profile or the state filter profile using a delta configuration to reduce how often the Item updates.
Or learn how to use your logs more dynamically (e.g. How to watch and look through logging).
You can turn off logging of Item changes entirely (only for all Items) by changing the logging level for openhab.event.ItemStateChangedEvent to ERROR.
You can turn off events.log entirely by setting the logging level for openhab.event to ERROR and removing/commenting out all the openhab.event.X lines in log4j2.xml.
You can set up a REGEX filter in the logging config to ignore this Item’s changes which will only remove this Item’s changes from events.log. Log filtering in OH 3 - #3 by markus7017