Home | News | Documentation | Download

TBrowser on lxplus runs slowly, perhaps due to font?

ROOT Version: 6.16
Platform: Ubuntu 18.04


I have recently had to do a factory reset on my laptop, and have run into some problems when trying to use ROOT on lxplus. My laptop runs Ubuntu 18.04, and in the past I had this problem, but managed to fix it although i now don’t remember how.

When I run a TBrowser on lxplus, it takes a few minutes to open, where before it would open much faster, and in general there is a sort of input lag present while i navigate the TBrowser. Once I have opened my decay tree in my root file, it works faster, but still slowly overall. When I try this from a windows PC on the same wifi, this problem is non-existent, the TBrowser opens fast and is responsive, so I do not think it is caused by a bad wifi connection.

I seem to remember that the last time i ran into this problem, it was due to the font of the tbrowser. It seemed as though the TBrowser was trying to display in the incorrect font (or a font that my laptop did not have possibly?) and this was causing the lag, as it had to look in other places to find this font. But ultimately, I am unsure what may be causing this and am not sure how to fix it, so any advice would be much appreciated, Thanks.

Hard to tell - and our GUI expert is on leave until the end of the month. I’ve asked @couet for help; maybe he has an idea, or an idea how to debug this.

Do the system logs show anything? Your ~/.xsession-... whatever it’s called?

Thanks for the quick reply. I don’t see a file like this anywhere in my directory, i’m unsure if it maybe has a different name, but nothing sticks out to me. Sorry for not being more helpful.

May be this can help:

In particular the The Xft stuff at the end.
If not @bellenot will know when he will be back.

I was referring to a file called .xsession-errors in your $HOME directory. But yes, @couet probably has the solution for you :slight_smile:

I have been trying the solutions posted in this thread before, i.e. making a .rootrc file as well as looking at the font root is using. Adding a .rootrc file had no effect, and the fonts that are listed are the same as in the thread, but I can’t change this as i dont have write permissions for the system.rootrc file since its lxplus.

My xft settings seem to be correct, although when i type ‘root-config --features’ the output doesn’t have xft mentioned anywhere, and again, i am not sure how to change this…