Oracle SQL Developer 3.2.09 is consuming lot of memory on windows 7
Add below lines to C:\Users\&lt;&lt;user&gt;&gt;\AppData\Roaming\sqldeveloper\4.2.0\product.conf

For 64 bit SQL Developer add:  

Add64VMOption -XX:+UseG1GC
Add64VMOption -XX:MinHeapFreeRatio=15
Add64VMOption -XX:MaxHeapFreeRatio=30


For 32 bit SQL Developer add:  

Add32VMOption -XX:+UseG1GC
Add32VMOption -XX:MinHeapFreeRatio=15
Add32VMOption -XX:MaxHeapFreeRatio=30


Restart SQL Developer.

To reduce the memory close only the results pane that has huge result set.

TIP: I typically increase JVM memory to 2 GB so SQL Developer does not crash for queries with large result sets. This can be done by adding below line to product.conf:

Add64VMOption -Xmx2048m