As I have suggested to Pathoschild, this could be solved by:

1. Decreasing how often calculations occur.
2. Updating in chunks.
3. Update asynchronously.

Fixed in develop for the upcoming Data Maps 1.4-beta.3.

Each data map now updates at a more nuanced rate (instead of the previous 60 updates/second) based on two per-map settings:

• UpdatesPerSecond: how often the map should update. The maximum is 60/second, but can be less than one to update less than once per second (or zero to disable the data map entirely).
• UpdateWhenViewChange: Whether to update when your viewpoint in the game changes, regardless of the UpdatesPerSecond value.

Here are the default settings: