Java Quick Starter (or JQS) is a feature that was added to Java in release Java SE 6 update 10. A process called jqs.exe will run in the background on Windows XP and Windows 2000 systems in order to allow quick startup for Java applets and applications.
JQS.exe does not need to run on newer Windows versions (such as Vista or Windows 7 and 8) because these operating systems offer their own pre-loading mechanisms.
JQS detects the most heavily used Java files and periodically pre-fetches them into memory. According to the official documentation of Java, JQS doesn't occupy more than 20 MB of RAM. As a result of this process, launching an application will be much faster as it requires much less disk input/output than it would without pre-fetching.
JQS.exe stops running when a laptop is running on batteries. JSQ can be switched off permamently through the Java control panel, which is one of the items in your Windows Contol Panel.