If you have Mapinfo (v15 and beyond 64 bit), you can do this very easily. So Mapinfo has come up with a new Raster module which gives excellent performance in handling large datasets.
It's built to handle large datasets. And that too in a very efficient manner.
Just to give you an example, I recently downloaded 5m resolution DEM data of Australia. The data is derived from some 236 individual LiDAR surveys collected between 2001 and 2015. This data covers an area in excess of 245,000 square kilometres. Total data was >3 TB.
Mapinfo Advanced very easily handled this much data and merged it into a single file. For my purpose I used new Mapinfo Raster format (mrr), but you can create output in other supported formats too.
Panning and zooming was very smooth and i had no issue visualizing the data.
Let me know if you need more information regarding the same.