I’ve run into similar resource drains before when running calculations on a server for a long time. It’s such a headache when the memory just keeps climbing without being released properly.
If you're still seeing that lag, one thing that helped me was to 'break down' the larger worksheets into smaller, modular files. Sometimes just pre-processing the data or splitting up the most intensive calculation blocks into separate steps helps the server handle the garbage collection a bit better. It’s a bit of a manual workaround, but it usually stops those random crashes when the resource usage hits a wall.