Even when this question is related to software issues you may wish to give a try to HardInfo, System profiler and benchmark, which will allow you to perform several benchmarks in order to gather information of your system and allows you to perform comparisons with other systems.
Linux should run with a considerable ease, the applications that you refer, unless the hardware is reaching its limits.
Most of the times a big memory size isn't enough if the memory speed doesn't fit your need for speed. Hard disk drives should be fast enough and facing no issues and generally: The system should be in good condition.
You don't lose anything giving this a try and may find something that would give you an idea of how is your system handling the physical resources.
Reach HardInfo at: http://hardinfo.berlios.de/HomePage
Here is a screenshot of my CPU Blowfish benchmark with two comparisons.
Additionally you can use a system monitor tool, like Conky or GkrellM in order to see your system's performance when attempting to run one of these applications. This won't fix your issues but will give you a clue on where to start.
I prefer to use GKrellM, so here is a screenshot of my system being monitored by this tool:
Here is a screenshot of Conky (from their site) featuring processes monitoring:
And when writing all this stuff I got a bulb turned on over my head, and I think that you should check what running processes are giving you problems when attempting to do what you wish. I mean: there can be a running process which can be requesting lots of processor or memory and this can cause your other applications to have problems.
Check this out in System Monitor: System/Administration/System Monitor. In the next screenshot you can see my google chrome demanding 122 MiB of the physical memory.
Who knows? you try it and let's see what happen. The more information you gather, the easier to find the solution.
Good luck!
The command below could provide at least a partial answer to your question.
/usr/lib/nux/unity_support_test -p
The command tests whether your video adapter will support Unity 3D. While it does not test 3D acceleration per se, it will at least test for the 3D features which Unity 3D requires.
And, what the heck, it comes with Ubuntu so all you have to do is open a terminal window and run it. ;-)
Here is an example of the output.
irrational@VBx64:~$ /usr/lib/nux/unity_support_test -p
OpenGL vendor string: Humper
OpenGL renderer string: Chromium
OpenGL version string: 2.1 Chromium 1.9
Not software rendered: yes
Not blacklisted: yes
GLX fbconfig: yes
GLX texture from pixmap: yes
GL npot or rect textures: yes
GL vertex program: yes
GL fragment program: yes
GL vertex buffer object: yes
GL framebuffer object: yes
GL version is 1.4+: yes
Unity 3D supported: yes
Best Answer
Ubuntu since 11.04 comes with benchmarks
glmark2andglmark2-es2which are quite good to perform simple benchmark (with shader) and are very light for download.glmark2 is actively developed by Linaro group. With each new release, new and more demanding benchmarks are coming. https://launchpad.net/glmark2
Benchmark also runs well on devices (ARM, OpenGL-ES2 based), so it's good (hardware) cross platform comparison. glmark2-es2 running on OMAP4/powervr Pandaboard http://www.youtube.com/watch?v=G5jg9D1lH5Y