STS slow for any action and consuming CPU

STS is consuming 30-35% CPU, even if you're not doing anything. In the task manager the status of the process is alternating from 'NOT RESPONDING' to 'IN EXECUTION', to 'NOT RESPONDING' again and so on... It takes from 30 seconds to minutes for the cursor get ready. It takes the same time to do any action, like save, build, organize imports, extract local variable, and so any action.... I'm not using Maven in this especific project. It happens with the option 'Build Automatically' on or off. It's consuming 880 MB of memory with just one simple project.