xhprof chart description

Question

For profiling, I have started to use XHprof. Nice tool! But, one question I can't answer by myself relates to chart content. Is there anyone who knows what color box and width of arrows on XHProf generated charts mean?

UPDATED It was not last question, here is couple new:

• Why on chart could be two or more red squares but only one of it will be connected by thick arrow with yellow squares ?
• What does it mean load:: in "Function name" column (on table mode view) ? is it means that PHP spent (cpu, mem etc) for loading that file ? Spent CPU time and Memory usage different from file to file, is it depends from filesize ? or content of file ? or both ? or something else ?
• What can you say (without detailes) when you'll see such charts ?

https://dl.dropbox.com/u/7017985/Screenshots/h4kq.png https://dl.dropbox.com/u/7017985/Screenshots/r1bc.png

is it possible to figure out anything without details, just looking on these charts ?

Answer 1

• Red squares are just items that are taking a significant amount of the total time. Yellow squares are the path the program took to get to them. If you're trying to improve performance, look at the red squares first :)
• Looking at my examples, load:: is a method call to load a particular file, so yes, different calls would depend on the size of the file loaded.
• As above, look at the red squares first to improve performance. On the second link, you may have some sql queries you can optimize.