How can I view what causes a page to load slow? i currently have the devel module on and i'm trying to figure out why my site is slow. I get the following info line:

Page execution time was 4661.1 ms. Memory used at: devel_boot()=3.27 MB, devel_shutdown()=65.39 MB, PHP peak=70 MB.

Is there a way to view why my page is taking 4661 ms to load? Here's a view of what the page is loading:
Yes you can figure out which function(s) spends more time in the execution by using a profiling module, then you can optimize that particular function(s)

Below are the available profiling modules in Drupal 7(AFAIK),


XHProf
Profiling


Personally I used XHProf and it helped us lot to improve the performance.


  XHProf is a hierarchical profiler for PHP. It reports function-level
  call counts and inclusive and exclusive metrics such as wall (elapsed)
  time, CPU time and memory usage. A function's profile can be broken
  down by callers or callees. The raw data collection component is
  implemented in C as a PHP Zend extension called xhprof. XHProf has a
  simple HTML based user interface (written in PHP). The browser based
  UI for viewing profiler results makes it easy to view results or to
  share results with peers. A callgraph image view is also supported.


In addition to this you can also look into Performance Logging and Monitoring module which was removed from Devel.