I think it depends on what you're trying to speed up. If you're talking about boot time, and if you have Malwarebytes and Spywareblaster set to start up as soon as you power on the computer, then you may see a few seconds improvement in operating system boot time. But if you're talking about a computer that's already gone through the boot process and is just waiting for you to give it some work to do (like opening a website or accessing your files and folders) I don't think you will see any noticeable improvement by disabling Malwarebytes or Spywareblaster.
Several months ago I tested my home computer in a completely non-scientific way. I did a factory restore using the recovery disks I made when I bought the computer. I installed all the Windows Updates, programs and applications like Office, SnagIt, Roxio, Microsoft Security Essentials, etc. I left everything at default settings including my paid version of Malwarebytes Pro. (Sorry, I've never used Spywareblaster.) My boot time was averaging 1 minute 45 seconds to about 2 minutes 10 seconds. Then I disabled everything at startup except for MSE, Malwarebytes and my Synaptics touchpad. Boot time decreased to about 50 seconds to 1 minute 10 seconds. Then I disabled Malwarebytes so it would be an on-demand scanner only. I did not see any difference in boot time. And as far as accessing websites once the boot process had finished, I did not see any appreciable difference no matter what was enable or disabled.
Having said all of this, each computer is different so maybe by disabling Malwarebytes and Spywareblaster you'll see a good increase in performance.