A lot depends on your computer specs.Windows 7 32 gig ram.!7-3370 cpu@ 3.4 GHz. Lens profile enabled and processing files from a d600 approx 24mbs no problem. 36 mbs is more than most photographers process?
My computer is midlevel in performance as shown below from the Lightroom system info listing:
Lightroom version: 5.0 [907681]
Operating system: (Build 9200)
Version: 6.2 [9200]
Application architecture: x64
System architecture: x64
Logical processor count: 8
Processor speed: 2.6 GHz
Built-in memory: 24567.1 MB
Real memory available to Lightroom: 24567.1 MB
Real memory used by Lightroom: 316.3 MB (1.2%)
Virtual memory used by Lightroom: 285.0 MB
Memory cache size: 36.6 MB
Maximum thread count used by Camera Raw: 4
System DPI setting: 96 DPI
Desktop composition enabled: Yes
Displays: 1) 1920x1200
Performance in Photoshop is good, but in general Lightroom is a bit sluggish, especially on startup.
Bill