Investigate cause of slow performance for TOMs with large databases

[rachel3834]

Is your feature request related to a problem? Please describe.
A number of projects have build TOMs with very large databases, including some that have customised the TOM DB.
A good example is the DESC-TOM, which ingested alert and classification information for a large set of simulated LSST alerts from several different brokers. The goal was to compare the classification data for the same alerts from different brokers, necessitating a large table join. Queries against this DB were very slow.

Describe the solution you'd like
Explore alternative DB structures that might offer better performance for these kinds of projects, for example no-SQL.

Additional context
This has been highlighed as an issue for the DESC-TOM and Sagguro projects.

This is related to:

• Speed up loading time of Observation page #595
• TargetList load time for non-superusers #598
• Revamp Observations List #1291
• Error deleting target in MOP. LCOGT/mop#241

Note
Snex has found some success with lazy-loading their plots to speed up page loads:

• Slowdown explore LCOGT/snex2#117