What are your Performance Preferences?
Please read these and proceed accordingly:
and here is my Mac's hardware specs
Model Name: MacBook Pro
Model Identifier: MacBookPro11,3
Processor Name: Intel Core i7
Processor Speed: 2.3 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB
Boot ROM Version: MBP112.0138.B02
SMC Version (system): 2.19f3
Well, one thing that jumps out is that you seem to have only one HD so you seem to be using your start up disk as Scratch Disk.
Be that as it may, I do not have this problem on my work computer which has much less space, and only one hard drive as well. The slowdown I'm talking about is signifigant the program becomes almost unresponsive and if it is exited it usually results in a crash report.