Displaying Markups (Waypoints, Routes, Lines, Shapes, and Tracks) on your screen uses your device's processing power, so having a lot of Markups displayed can cause the app to run more slowly or crash.
Some Markups use more processing power than others. For example, a Track is a series of Waypoints linked together, so even though a Track is a single file, it uses a lot more processing power than a single Waypoint.
There are a couple of strategies you can use to avoid running into these issues:
Delete unneeded Markups: If there are markups you don't need anymore, we recommend deleting them completely from your account. To delete Markups, open the My Content Menu.
Tap the Select button at the top of the menu.
Tap the check-boxes next to the Markups you want to delete, then swipe left on the bottom row of buttons and tap "Delete."
Export and store: If you don't plan on using a set of Markups anytime soon, but don't want to lose them forever, you can use the Export function in Web Map to store them on the computer as a KML or GPX file.
Please be aware that KML and GPX files do not support onX colors and icons, so only the position and name associated with a Markup will be saved in the exported file.
Exported Markups can be restored (except for the colors and icons) using the Import feature.