I'm not a maven or surefire expert, but I think the surefire plugin executes every test file it finds in under your test directory. This means the default configuration doesn't need test suites. Surefire finding and then running your test suite PLUS your other tests could be the cause of the 2x the number of tests to be run. But I don't know why it would take more than twice as long to run.
If this is the case, you can tell surefire to only run your test suite:
<configuration>
...
<includes>
<include>AutoTestSuite.java</include>
</includes>
</configuration>
instead of **/*.class
EDIT: Because Jacoco has already instrumented the classes you need to use
<configuration>
...
<includes>
<include>AutoTestSuite.class</include>
</includes>
</configuration>
instead otherwise you don't run the instrumented version.