Window handle mechanism feels tight
You have to be careful with window lubricants. If they are greasy/sticky, they will attract dust and dirt (and also get on your clothes).  

They make graphite lubricants (generally for locks) that will not leave a greasy residue.   They also make "graphite paint" which is basically paint resin loaded with graphite instead of pigment and filler.

However in a window, the resistance is less likely to be from pivoting points and more likely to be from sliding points. Graphite paint is a good choice for those. The paint will powderize as the surfaces spall, and that dust can still stain clothes, but at least it isn't sticky.