Wall of text alert:
Spoiler
With a vanilla project, the game seems to run much faster than before on my netbook which has an Atom Z3775 processor and 2GB ram. I think it's unrealistic to expect old computers to run RMMV as it would RM2k3, especially (but not limited to) the fact that MV uses GPU and not CPU to process the games. After all, MV is not RM2k3 with mobile support. It's a completely new and modern engine.
As for the plug-ins being broken, I'm sure the scripters are working to adjust their scripts according to the new framework. They just need time since MV was just updated yesterday, and they're mostly doing this on their free time for free. Honestly, I would have been more surprised if this update didn't break any plug-ins, considering the amount of changes it needed to optimize MV better compared to the previous versions, as well as the update to Pixi4.
I can only suggest for others to keep the base scripts from version 1.2 for their current projects until the scripts have been updated. Updating to version 1.3 won't overwrite the scripts from the existing projects until you do it yourself.
As for the accusations that the MV devs don't test their engine before releasing or updating it, I think it's unfair since every decent game making engine out there has to be updated and bugs addressed, plus they have a larger team to work on their more expensive and sometimes royalty-required engines. The bugs aren't as obvious as they are in RM engines because the others like GM, and Unity require at least some level of scripting ability, and users normally blame themselves for broken functions until the company fixed them. Functions are automated in RM so it's faster and easier to spot errors and mistakes.
Let's all be cordial here and help one another out. From the fixes and features that are being introduced in each version, I feel that the devs are listening to us reggarding bug reports and feature requests. They just need time to address the issues. Rome wasn't built in a day, after all. ;)

As for the plug-ins being broken, I'm sure the scripters are working to adjust their scripts according to the new framework. They just need time since MV was just updated yesterday, and they're mostly doing this on their free time for free. Honestly, I would have been more surprised if this update didn't break any plug-ins, considering the amount of changes it needed to optimize MV better compared to the previous versions, as well as the update to Pixi4.
I can only suggest for others to keep the base scripts from version 1.2 for their current projects until the scripts have been updated. Updating to version 1.3 won't overwrite the scripts from the existing projects until you do it yourself.
As for the accusations that the MV devs don't test their engine before releasing or updating it, I think it's unfair since every decent game making engine out there has to be updated and bugs addressed, plus they have a larger team to work on their more expensive and sometimes royalty-required engines. The bugs aren't as obvious as they are in RM engines because the others like GM, and Unity require at least some level of scripting ability, and users normally blame themselves for broken functions until the company fixed them. Functions are automated in RM so it's faster and easier to spot errors and mistakes.
Let's all be cordial here and help one another out. From the fixes and features that are being introduced in each version, I feel that the devs are listening to us reggarding bug reports and feature requests. They just need time to address the issues. Rome wasn't built in a day, after all. ;)

Wall of text out. :p