Movement reduction due to armor type and weight

[Gwiber]

If a PC is wearing a heavier suit of armor (in this case field plate), which drops a regular person moving 30ft. to 20ft., does their movement drop a further 10ft? With a medium load?

[MrCab]

From the section on Carrying Capacity in chapter 7 of the core rule book:

Quote:

If your character is wearing armor, use the worse figure (from armor or from load) for each category. Do not stack the penalties.

Emphasis mine. So you don't get slowed down an additional 10 feet, you just use the slower of the two speeds - speed after encumberance from armor, or speed after encumberance from carrying a lot of stuff.