There isn't checkout on SharePoint lists (there is on document libraries) - SharePoint uses optimistic concurrency rather than pessimistic concurrency - e.g.
- User A opens up edit form and starts editing
- User B opens up ...
- User A saves
- User B clicks save but SP warns them that the data has
changed since they started editing and will make the user B view User A's changes and re-enter.
For most use cases this is sufficient as an edit on a list item will generally be started and completed pretty quickly (as opposed to a document that could be being edited for hours or days) so the chance of this occurring is small.
Can I ask what use case and load that you're expecting this to be a problem for? Is this actually causing a problem now or are you perhaps over engineering? (no offence intended)