Require understanding on how reflects work

I am new to Dremio and am work with a large dataset. The run performance is incredibly slow. I am trying to utilize reflects to gain performance efficiencies but this has greatly increased the response time. I need assistance in understanding the concept of data reflections and how performance may be improved

I would suggest this tutorial:

And this white paper:

Also tell us where you have Dremio deployed. Your issue may simply be that your environment is underprovisioned for the size of the data you are querying.