This will result in extremely poor performance in the backend when you have more than a few thousand items, especially on shared hosting or servers with a stock MySQL/MariaDB (=unoptimized) configuration. Besides, there's a tag filter option in the K2 Settings (like the category filter) which should be sufficient for your needs. This option is off by default in the K2 Settings under the "Administrator" tab: jmp.sh/5tm9nas