Ever since updating, starting up my Macbook pro takes a very long time, can this be fixed?

Select Macintosh HD as the Startup Disk.

“Set the default startup disk” http://support.apple.com/kb/HT1310

Reset PRAM. http://support.apple.com/kb/PH18761?viewlocale=en_US&locale=en_US

If it takes long time try to restart your computer in Safe mode by taking these steps:

- Click on the Apple sign() at the upper left corner of the Desktop, select 'Shut down' from a drop-down menu;

- Wait until your computer turns off, then press the Power button(⌽);

- Immediately after you hear the startup tone, press and hold the Shift(⇧) key. It should be held as soon as possible after the startup tone, but not before the tone;

- Release the Shift(⇧) key when you see a grey Apple sign() and the progress bar below;

This will force the system to perform several maintenance routines and load essential system software.

Once you've seen the Desktop, start a Disk Utility scan to detect and repair file system errors:

- Open Disk Utility application:

1. Click on Finder at the bottom of your Desktop;

2. Select Applications folder from Finder's left sidebar and then open Utilities folder (or press Command(⌘)-Shift(⇧)-U), double-click on Disk Utility icon;

- Choose your main hard drive from the left sidebar ('Macintosh HD', usually);

- Click on 'Verify Disc' at the bottom right corner, your Mac will perform a diagnostic test. Click on 'Repair Disk' if prompted to fix problems, or follow instructions given on the Disk Utility window;

If this will not help try to reset PRAM

OS X Yosemite: Reset your computer’s PRAM

Griggs Project wrote:

Starting up my macbook now takes a long time, can this be fixed?

What is your definition of "a long time?"

The startup now takes a couple of minutes. It will take 30 seconds or more just to get through the gray screen with the progress bar. If it is longer than that, you may have a problem. Thunderzzz has covered the two things I would initially suggest.

If that doesn't help, then you need to look for incompatible third-party things that launch at startup or in the kernel.