You might want to try installing version 1.7 (oracle's one, not openjdk), and making sure it is the active version using update-alternatives and java -version.
Do note, however, that java is NOT a fast technology. Your applications are compiled to intermediate bytecode which needs to be interpreted by a fairly heavy application called the JVM. Although I don't remember ever having experienced multiple seconds of interface lag, I do know the GUI's written in java tend to be slow.
I've never noticed any difference between windows 7 and ubuntu/opensuse though (each 64-bit), but that might be due to the version: I always get the latest official java sdk (that is, from Oracle).
Although this might not be the answer you'd like to hear, if you don't explicitely need java (which you would if you were targetting mobile devices, I suppose) and/or if performance is important for your application, you might want to look for a native-compiled alternative. C++ with Qt would be an excellent alternative, if you're familiar with C++. It keeps your application cross-platform, without affecting the general performance.
Mono/C# comes with an option to precompile the bytecode, so you basicly have a native executable with the mono runtime included (heavy at startup, but faster than java at runtime).