using the "Sync and exit" function delays every OS operation for about a minute, although resources usage is minimal

What steps will reproduce the problem?
1. Open CryptSync (already configured with a folder pair with approx. 50GB of 
mixed file types)
2. Click "Sync files and exit"
3. Wait for the sync progress dialog to begin.

What is the expected output? What do you see instead?

Expected: All other Windows apps and functions should run normally.

Actual result: Although the progress windows displays normally and Windows UI 
responds normally as well, all other Windows functions perform with a 30 
seconds - 1 minute delay each, for example run any program, open any folder, 
open any webpage, close any program, terminate any process, etc - every 
operation with a 30 seconds - 1 minute delay.

What version of the product are you using? On what operating system?

Windows 8.1 Professional
CryptSync 1.2.0.264

Please provide any additional information below.

1. The processor levels keeps low during all the process, around 10%, the HDD 
access rate also normal, memory usage also low. Nothing indicates any 
"resource" bottleneck, rather, some programming issues (maybe too many 
unnecessary iterations or waiting for something too much?)

2. When looking at the CryptSync processes in Task Manager, there are 2 child 
7-zip processes "7z.exe", which most of the time do nothing (processor usage at 
0% for approx 1 minute, then for a few seconds levels spike to 100%, then the 
7-zip processes terminate and another 2 7-zip processes start, also waiting at 
0% processor level for a bout a minute)
All this indicates that the general delay in every Windows operation is also 
happening with the 7-zip processes.

3. This only happens when using "Sync files and exit mode", i.e. with the 
visual progress dialog. The issue does NOT happen on background sync.
When using background sync, everything goes fast, each 7-zip process runs for a 
few seconds, then terminates and another 7-zip process is created.

Resume: When using the "Sync and exit" function, something delays every OS 
operation for about a minute.

Original issue reported on code.google.com by e.income...@gmail.com on 11 Aug 2014 at 9:54

ECToo / cryptsync

using the "Sync and exit" function delays every OS operation for about a minute, although resources usage is minimal #123