Observed in Builds: 201508250002, 20150823000 and 201508200002.

Hardware specs

mac Book Pro retina Display Mid 2012
OS X Yosemite (10.10.4 (14E46))
Memory: 16 GB 1600 MHz DDR3
Processor:2.7 GHz Intel Core i7
Hard disk: 500GB SDD
Graphics: 
Intel HD Graphics 4000 1024 MB
NVIDIA GeForce GT 650M 1024 MB

Observation:
With NetBeans running and in focus Press CMD+Q or Using mouse click the close button on top left of NetBeans window.
The NetBeans Window immediately disappears but the NB icon in the dock does not go away till about 4-5 seconds. 
I also checked the activity monitor, the process disappears after 4-5 seconds


Observation scenarios where the above behaviour was seen

1. Only NetBeans is the active application
2. Disconnected from Network
3. NetBeans is running along with other applications.
4. Forced the Mac to not switch Graphics from Intel to NVIDIA

Steps to reproduces
Scenario 1
1. Shutdown all applications running (including NetBeans if running)
2. Clean cache and userdir
3. Start NetBeans
4. Close NetBeans

Steps to reproduce
1. Shutdown all applications running (including NetBeans if running)
2. Start NetBeans
3. Open a few projects (including a Maven project)
4. Do some builds, run some projects
6. Stop running projects
5. Let Maven indexing complete
6. Close all projects
7. Shutdown Netbeans

Any other application showing similar behaviour
1. All my Microsoft Apps (Word, PPT, Excel and Lync) exhibit same behaviour when connected to the network. But when disconnected from Network - they shutdown quickly.

Any other Java applications or services showing similar behaviour
1. I tried with Apache tomcat - started tomcat process and stopped it using the startup.sh and shutdown.sh scripts. It was near instantaneous.

Any Other process I thought was hindering
1. Verified and repaired mounted disks
2. Stopped backup services
3. Stopped Anti-Virus 
4. Perhaps it was because of Graphics switch. So I prevented the Mac to switching to NVDIA.