MacBook – WD Passport External USB Drive – Really slow on Macbook

The standard for Lion is GUID partition scheme with one volume HFS+ Journaled.

The journaling is preferred since the filesystem can be checked in moments when the system reboots rather than running an exhaustive fcsk each time the drive is unmounted cleanly.

You don't want a case sensitive file system as some programs are not ready for dealing with fiLe.txt being different than file.txt - you'll need extra time for testing / finding bugs if you work on a filesystem that's different than the majority.

You can refer to another question on when GUID/GPT might be better than APM: When is the GUID partition table (GPT) preferred over Apple partition map (APM) for external drives?

This seems like an issue with the chosen file system.

What file system did you choose when formatting the hard drive? If it's not HFS(+), FAT in any fashion or NTFS you cannot read it on OS X without additional software. If it's Ext, you could go with Paragon's Ext for Mac (but it costs some bucks).

In future, best choose exFAT when formatting an external hard drive if you need to use it on different operating systems. It both allows rather large files (which is heavily limited in FAT32), but can be both read and written in all important operating systems.