Try running the benchmark under Help in MC, then paste the results here.
This is the score, I have no clue if the numbers are normal or not.
=== Running Benchmarks (please do not interrupt) ===
Running 'Math' benchmark...
Single-threaded integer math... 17,922 seconds
Single-threaded floating point math... 11,083 seconds
Multi-threaded integer math... 3,815 seconds
Multi-threaded mixed math... 1,657 seconds
Score: 551
Running 'Image' benchmark...
Image creation / destruction... 0,445 seconds
Flood filling... 1,311 seconds
Direct copying... 0,598 seconds
Small renders... 4,885 seconds
Bilinear rendering... 1,887 seconds
Bicubic rendering... 0,633 seconds
Score: 2254
Running 'Database' benchmark...
Create database... 0,465 seconds
Populate database... 4,424 seconds
Save database... 0,976 seconds
Reload database... 0,275 seconds
Search database... 3,627 seconds
Sort database... 3,212 seconds
Group database... 2,024 seconds
Score: 1433
JRMark (version 20.0.27): 1413