Hello,
well, I would consider this response time as "not normal" for a "sufficiently dimensioned" Alfresco installation. But reading that you only allocated 2 GiB RAM to Alfresco Tomcat, I am very hesitant to apply "sufficiently dimensioned" to your environment. While 2 GiB can be enough for evaluation purposes and simple, low usage scenarios, it can quickly be exhausted when loading large volumes of data (and doing that in parallel). Furthermore, the 2 GiB is only the total and is separate into various memory areas at runtime. If some of those areas run full during runtime, you can run into issues such as "GC thrashing" which means the application is mostly dealing with cleaning up memory to use, filling what little it could clean up immediately and starting over… This causes high CPU usage and massive increase of response times (GC involves "stop-the-world" pauses to the entire application).
Such a phenomenon can typically be diagnosed when looking at the runtime with a JMX client. Try allocating 1 - 2 GiB additional RAM and see what happens - if response times radically improve, you did suffer from "GC thrashing".
Regards
Axel