I am also having the same problem, especially when using the NTA module. The graphs are always on loading for few minutes before it is loaded and in some cases the graph won't load finish at all and stuck at loading forever.
SolarWinds is running on HP ProLiant DL160 G6 with Intel(R) Xeon(R) CPU X5680 @ 3.33GHz 3.33GHz, 4gb RAM and Twin 300GB running on Raid 1+0. SQL server is on a seperate machine.
The SQL server is using the same hardware as the SolarWinds server.
Hopefully this can be resolved. My clients are getting restless regarding this.