Introduce ParkourSnapshots, which exist in a folder 'snapshots', with the file name being the players UUID.yml.

• When the player leaves server, create snapshot details file (under a different thread)
• When the player joins server, check if snapshot exists and load it, set their time to the difference between leaving etc.
• When the player leaves the course, (based on config) check if snapshot exists and destroy it OR save snapshot.
• When the player joins a course, (based on config) if snapshot exists, load it and place them back where they were.

It's important to keep an accurate account of how many players are on a course online. Physical snapshots will mean less memory usage. Creating / Saving snapshot files might cause a performance impact, so look into that.