do you have Adobe Photoshop? or some else program for pictures?
for example if you have Adobe Photoshop,you have to open picture,on taskbar you have to click on "Image" then "Image Size".Then you have to write 100pix or 80pix,it depends->then click OK.The picture will be smaller.On taskbar again you have to slick on "File",then "Save As",now,the most important thing is that when you're saving pic,when computer ask you about pic quality,click on "Low" quality.
Picture will be smaller and not heavy like before.
After this you've to upload pic,when you upload pic,right click on pic->"Properties"->copy URL adress
Skip in your controls on this forum->profile->avatar settings->paste URL adress and that's it!
I don't know did you understand this,I just try to help you...Also,I can resize this pic for you.