mazumo :
what about something like browsing with much tabs and background application like antivirus and some application working at background does the HT will be useful at this case or not ?
So long as it's spawning extra threads/processes, and there's some blocking (waiting for I/O, memory, etc), yes HyperThreading will help (in essence it's interleaving 2 processes/threads onto a single core so that thread B can run when thread A is blocked waiting for I/O, etc).
I built my parents a PC based around an i3-4330 running Linux Mint, and it's really responsive - it'll play a silly number of YouTube videos simultaneously, and you can see all 4 "cores" in use.