Slow VNC. Where's the bottleneck?

Question

I have two computers in a LAN, one for leisure and one for hobby. The latter I connect to via Remmina VNC.

This is what the desktop of the hobby computer looks like.

The speed of my mouse cursor is okay, but dragging around a window is very slow and choppy. As you can see in the upper right corner, The CPU shows that it's around 20% (on the Arch Box), that is, while I drag the terminal around. Otherwise it sits at under 1%. I have it on full-screen 1920x1080 and because I program on it, so I like to keep it at that size.

What do I need to do to get it to run at an adequate speed? If dragging windows around would go smoothly I'm happy.

Should I change settings? Use another app/protocol? Is it due to make Cat5 cables? Low CPU power?

These are my settings for Remmina.

Details LAN

One home/client computer

• CPU benchmark 25xx according to cpubenchmark (terribly slow, I know)
• Ubuntu 16.04 Unity 7
• Fritz!Box Powerline 1000E
  • Cat 5 cable (1m)

One hobby/server computer

• CPU benchmark 18xx according to cpubenchmark
• ArchBang OS
• Cat 5 cable (10m)

FRITZ!Box 7360 Modem

• 2x 1Gbit LAN connection
• Fritz!Box Powerline 1000E
  • Cat 5 cable (0.3m)

Solution

We need more information for a better answer, but based on what you have posted, it seems like that the 20% utilisation is occurring on your Arch box. I do not think this is a VNC problem, but seems more like that the Arch box is being taxed to move that terminal window around before VNC transmits the screen over your network connection. In other words your Arch system is rendering then transmitting the pixels on the screen for the Arch box. During the re-rending of the screen position, it is the CPU of the Arch box that being used to redraw screen.

Since VNC just retransmits that screen my advice is to use a more efficient protocol such as RDP or NX which would offload some of the rending load to the client Ubuntu system.

https://wiki.archlinux.org/index.php/FreeNX

You might want to be a bit clearer in defining your problem. Which computer has the 20% cpu utilisation which moving the Window around? Also what are specifications of each of your computers, actual CPU, amount of RAM, video chipsets?

It may well be the case that your computers are just not up to the task.

Comments

[Law29]

Possible duplicate of How can I make VNC faster?

[Law29]

You say that the terminal is slow, why don't you use ssh?

[Folaht]

I mean dragging around windows. And yeah, I realize it's a possible duplicate, but I don't know if it's due to my cables or VNC settings.

[Folaht]

It's the Arch Box that has 20% cpu utilisation. I'll check if it runs smoothly on the Arch Box soon. Your FreeNX suggestion sounds very promising by the way.

[Folaht]

It works fine non-remotely. I'm going to try out FreeNX soon. I think you've got the right answer.