Some more detail would probably help. Windows 7, CF9 and Java are 32 or 64 bit?
For bit check CF Java via Server Settings > Settings Summary > Java VM Name EG Java HotSpot(TM) 64-Bit Server VM
Sometimes Java matters are logged to ColdFusion9\runtime\logs\coldfusion-out.log . Any Java warnings or error messages in that log file?
JVM logging can be useful to know what is going on Java memory wise. I think there are many resources to search on how to do that tho if you want some direction reply the thread and I am sure to be able to point you to some links.
Indeed 1.5Gb is not a lot of RAM but it may not be apportioned well to suit your needs. Other than JVM logs it would also be interesting to know what Java version (A) you are using plus your JVM arguments (B)?
A) Server Settings > Settings Summary > Java Version EG 1.6.0_29
B) ColdFusion9\runtime\bin\jvm.config >
# Arguments to VM portion
java.args=-server -Xmx512m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=192m -XX:+UseParallelGC
That should start to help you along, Carl.