for the backup time you might show a predicted time the backup might finish?

Gooly

Backing up takes a long time.

Like many other you show  percentage of  how much has been finished already.

Why don't you add an estimated time (TimeEstim) the whole thing will finish.

You even can add a so called 1-pole-low-pass-filter:

1) t = TimeStart + (TimeNow-TimeStart)/%-finished;

2) TimeEstim = TimeEstim + (t-TimeEstim) * Const;

with Const < 0.5.

Point-2) is equivalent to an average of the most recent n ( = 2/Const + 1 ) values.

So if Const = 0.5 n would be 3, Const=0,4 => n= 4, ...

So the smaller Const the smaller are the changes of TimeEstim. 

Regards,

Gooly