I know you must have followed the guides for seting up a laptop for recording,, but make sure there are no background processes running. ON laptops this is critical. I found the BAttery managment and wi fi are huge offenders. Go to task manager and see whats running. 
 
Download and run http://www.resplendence.com/latencymon
 
 

I don't know how good or bad these results are but:
Here's the throughput for my C drive:

 
And my A (audio) Drive:

 
I have another thread going, if anyone cares to chime in:
http://forum.cakewalk.com/Same-file-plays-fine-in-X3e-but-in-Platinum-I-get-dropouts-and-glitches-Windows-7-64-m3464600.aspx
 

Noel Borthwick [Cakewalk]
 
Platinum actually uses less "horsepower" than X3. We have several benchmarks to show it.
If you are dropping out on recording you most likely have a systemic problem that happens to show up when recording. How many simultaneous tracks are you trying to record and what audio interface and latency settings are you using? As I said its likely related to your hard disk throughput or perhaps power management.

I was trying to record ONE track, while playing back about 15 tracks.  Using a Roland Studio Capture with the buffer set almost to MAX.

Anyway, I think we're getting a bit sidetracked here because the OP mentioned that his system works fine in Sonar X3 (just like in my case), so one would expect the system to be working similarly in Platinum. Shouldn't Platinum be the focus here and not the computer?

Cactus Music
I know you must have followed the guides for seting up a laptop for recording,, but make sure there are no background processes running. ON laptops this is critical. I found the BAttery managment and wi fi are huge offenders. Go to task manager and see whats running. 
 

 
There are some things running in Windows 10 that I can't stop, like that damn Cortana.  It just starts up again.  I didn't think about the wireless adapter though, so that may be it.
 
Seriously though, I don't think I'm going to risk using my laptop to record drums anymore. Not until I get a more powerful laptop that is really configured for recording anyway.  There are just too many "moving parts" that have to be aligned "just so" in order to get everything to behave.  I need to know that things are going to work before I start.

pmarangoni
Seriously though, I don't think I'm going to risk using my laptop to record drums anymore. Not until I get a more powerful laptop that is really configured for recording anyway.  There are just too many "moving parts" that have to be aligned "just so" in order to get everything to behave.  I need to know that things are going to work before I start.

I've been recording 8 tracks of live drums on my laptop, which is way older and slower than yours (2009) without any issues for years. I thought you said everything was working fine in X3? Why not just use X3 until you figure this out?
 
And yes, you MUST have your network adapter (wifi) OFF.

microapp
+1 to CrystalDisk utility.
I would get Resplendent Software's Latency Monitor as this may narrow down what is the culprit. It is free.

+1 to LatencyMon

pinguinotuerto
I don't know how good or bad these results are but:
Here's the throughput for my C drive:

 
And my A (audio) Drive:

 
I have another thread going, if anyone cares to chime in:
http://forum.cakewalk.com/Same-file-plays-fine-in-X3e-but-in-Platinum-I-get-dropouts-and-glitches-Windows-7-64-m3464600.aspx
 

Your scores on the audio drive are close to what I get on my WD 7200rpm SATA 3GB/s audio drive.  It does not look like this would be a bottleneck on a few audio tracks.

abacab
Your scores on the audio drive are close to what I get on my WD 7200rpm SATA 3GB/s audio drive.  It does not look like this would be a bottleneck on a few audio tracks.

 Yeah, I don't think my issue is hardware related. Thanks for the tip and for looking at my results. When I get to the studio, I'll delete my 32 bit plugins and see. If this is the issue with Platinum, then someone from Cakewalk should let us know (if they know) that Platinum doesn't play nice with older plugins that X3e can handle without issues.

pinguinotuerto

abacab
Your scores on the audio drive are close to what I get on my WD 7200rpm SATA 3GB/s audio drive.  It does not look like this would be a bottleneck on a few audio tracks.

Yeah, I don't think my issue is hardware related. Thanks for the tip and for looking at my results. When I get to the studio, I'll delete my 32 bit plugins and see. If this is the issue with Platinum, then someone from Cakewalk should let us know (if they know) that Platinum doesn't play nice with older plugins that X3e can handle without issues.

This is just my 2 cents ...
 
You and the original poster's laptops ran Sonar X3 OK.  Your problems began when you both switched to Platinum.
 
Your Intel Core i7 can turbo up to 2.8GHz, with a max memory bandwidth of 21GB/s.
http://ark.intel.com/products/43122/Intel-Core-i7-720QM-Processor-6M-Cache-1_60-GHz
 
Assuming that your hard drive is not the bottleneck, and the latency monitor shows green, you should be good to go.  Problem is that you are not good with Platinum.
 
The other suggestion here, like turning off unnecessary start up background programs and unplugging wi-fi could help. 
 
But I'm also starting to think that maybe something changed with how you use the audio drivers in Platinum.  Are you using ASIO with the same settings as X3?