# Long delays before showing the result in a notebook

I'm new to Mathematica. I have Version 10.3.0 running under Windows 10, 64-bit.

If I open the 10.3.0 kernel and type 2 + 2 Shift Return I get an immediate answer.

If I open the main program and open an existing notebook and then type 2 + 2 Shift Return, there can be a noticeable delay of perhaps tens of seconds before the answer appears. I see a bolded square bracket on the far right of the line.

My computer is pretty fast with SSD disks and 8.00 GB RAM and I'm not used to seeing delays like this.

Question

Is this a common phenomenon?

What could be going on behind the scenes in a notebook that takes so long?

Is there some simple action I can take to speed things up?

• I think it's normal. It does the same thing on my laptop (i7. SSD, 16GB RAM, ecc). Even just evaluating on a new empty notebook. It's just for the first evaluation though, after that it goes smoothly. – glS Nov 6 '15 at 5:09
• The thing with modern Mathematica is that there is some setup being done behind the scenes, so there's a slight delay during the first evaluation. If you're still seeing these delays for In[2], now that's a different question altogether... – J. M. will be back soon Nov 6 '15 at 5:20
• @J.M. Maybe we should keep a generic topic about that, asked more than once before. Mathematica computes too slowly at the start of a session – Kuba Nov 6 '15 at 6:44