Interestingly, this hotfix comes in the form of a macro to clean up your files. The issue as stated on the Autodesk Knowledge Network is:
In Revit 2015 the performance of some file is very slow. This means that
opening material browser may take an extremely long time or Revit will
hang. Typically you cannot execute the “Purge unused elements” command
as well, because Revit will freeze. 


Every time you edit a family and load it back in > overwrite > the
number of materials will grow substantially. For example after 5 or so
subsequent reloads in our sample file it jumps from 15551 to 186623
materials.

We have seen this most commonly when editing titleblock familes in the German and Japanese version of Revit. 


Download the macro:
DeleteStandardMaterials.zip

Please go through the process below to clear out the extra materials:

  1. Close Revit.
  2. Extract the zip file: It will contain a DeleteStandardMaterials folder with two subfolders (AddIn + Source).
  3. Copy the AddIn + Source folders on the following path:
    C:ProgramDataAutodeskRevitMacros2015RevitAppHookupDeleteStandardMaterials
  4. Start Revit.
  5. Open the file.
  6. Open Manage/ Macro Manager/ Application Tab: The macro should
    show up in the Macro manager under application > macros as
    “DeleteStandardMaterials”.
  7. Select here “Execute” and start the command “Run” > This will delete Standard Materials.

After these steps use Save As to save the file with a new name.

Here are 2 videos showing the steps:
https://screencast.autodesk.com/Main/Details/5bfa2fff-3443-45e0-a156-4c530c594c28
https://screencast.autodesk.com/Main/Details/fb7eaa0a-b529-47b7-9e35-7d42c3944a0b

Main page:
File performance problem in Revit 2015 | Search | Autodesk Knowledge Network

Heads-up:
Be Revit – Do Family Planning: Revit streikt / Datei wird immer größer und reagiert nicht mehr?

Readme:
http://download.autodesk.com/SWDLDDLM/Updates/ReCap/Autodesk_ReCap_2015_Hotfix1.html

1.    This hotfix addresses Heartbleed vulnerability – a security bug in the open-source OpenSSL cryptography library. Heartbleed is registered in the Common Vulnerabilities and Exposures system as CVE-2014-0160. For more information, please visit the CVE dictionary at http://cve.mitre.org.
2.    This hotfix fixes the bug in ReCap that project file might be corrupted or deleted when computer went to sleep or shut down during scan importing.
3.    This hotfix fixes the bug in ReCap that PTG with only intensity are imported as all-black.
4.    This hotfix adds the support for US Survey unit in ReCap.
5.    This hotfix fixes the bug in ReCap that project cannot load on A360 if map images do not exist in Temporary Cache when publishing.
6.    This hotfix fixes the memory allocation error in ReCap during registration.
7.    This hotfix fixes the bug in ReCap that export might fail under certain conditions.
8.    This hotfix fixes the bug in ReCap that region is not displayed properly when reopened after deletion of points.
9.    This hotfix fixes the bug in ReCap that project save as function is not copying all support files to destination folder when merging several projects.

This hotfix resolves three issues:
– Problems resulting from operations that involve clicking in the first column of the Clash results grid, such as collapsing/expanding groups, dragging clashes and resizing columns.
– Issues with material and transparency inconsistency when importing FBX files.
– Issues with the automatic selection of the correct Rendering engine (Presenter or Autodesk)

Downloads at:

this link

via

Navisworks/BIM 360 InfoCenter: Navisworks 2014 Hotfix 3

Quick fix for Revit 2012:

  1. Close Revit
  2. Go here, download and extract ZIP
  3. Go to Revit 2012 Program folder and rename AdWindows.dll to AdWindows.dll_OLD
  4. Copy AdWindows.dll from the extracted folder to the Revit 2012 Program folder
  5. Open Revit Architecture 2012 – your ribbon problems should be fixed

For Revit 2013 links, see below:
Ribbon behavior problems occur in Revit 2012 and 2013 after the installation of Microsoft .NET 4.5, which is one of the pre-requisite for Revit 2014. This is why this problem is typically encountered after Revit 2014 is installed side-by-side with a previous version of Revit. For those using Revit 2012, the Autodesk Revit 2012 – Ribbon behavior due to .Net 4.5 installation hotfix will resolve this problem. And for Revit 2013 users, the fix is included in the latest update releases, which are available from the following links: Revit Architecture, Revit MEP, Revit Structure, andRevit.

Tony Michniewicz
Autodesk Revit QA

Related forum thread:
http://forums.autodesk.com/t5/Revit-Architecture/Revit-2014-Corrupts-Revit-2012-and-2013-Ribbon-Menu/td-p/3876942/page/2

This hotfix addresses issues with meters to feet conversions indexing FARO point clouds and improves product stability when manipulating large or complex point clouds.

Make sure that Update Release 2 has been applied prior to adding the hotfix. Verify that the build number of Revit 2012 is 20110916_2132.

The Readme contains the latest information regarding the installation and use of this update. It is strongly recommended that you read the entire document before you apply the update to your product. For your reference, you should save the Readme to your hard drive or print a copy.

Readme (htm – 97Kb)
Revit2012_Point_Cloud_Hotfix.zip (zip – 3810Kb)

 via
Autodesk – Autodesk Revit Architecture Services & Support – Hotfix – Autodesk Revit 2012 – Point Clouds

Hotfix – Autodesk Revit 2012 – Error with linked model visibility with custom settings

This hotfix addresses issues related to a crash in RevitMFC.dll

Make sure that Update Release 2 has been applied prior to adding the hotfix. Verify that the build number of Revit 2012 is 20110916_2132.

The Readme contains the latest information regarding the installation and use of this update. It is strongly recommended that you read the entire document before you apply the update to your product. For your reference, you should save the Readme to your hard drive or print a copy.

revit2012_link_hotfix.zip (zip – 4433Kb)
Readme (htm – 86Kb)

via
Autodesk – Autodesk Revit Architecture Services & Support – Hotfix – Autodesk Revit 2012 – Error with linked model visibility with custom settings

This hotfix improves product stability when working with large datasets.

Make sure that Update Release 2 has been applied prior to adding the hotfix. Verify that the build number of Revit 2012 is 20110916_2132.
NOTE: This hotfix applies to the 64-Bit release of Autodesk Revit 2012 only.

The Readme contains the latest information regarding the installation and use of this update. It is strongly recommended that you read the entire document before you apply the update to your product. For your reference, you should save the Readme to your hard drive or print a copy.

Readme (htm – 84Kb)
revit2012_mem_hotfix.zip (zip – 11247Kb)

via
Autodesk – Autodesk Revit Architecture Services & Support – Hotfix – Autodesk Revit 2012 – Improves stability when working with large datasets (64-bit only)

This hotfix restores the ability to apply material family parameters to faces of family elements using the Paint tool.

Make sure that Update Release 2 has been applied prior to adding the hotfix. Verify that the build number of Revit 2012 is 20110916_2132.

The Readme contains the latest information regarding the installation and use of this update. It is strongly recommended that you read the entire document before you apply the update to your product. For your reference, you should save the Readme to your hard drive or print a copy.

revit_2012_material_hotfix.zip (zip – 4430Kb)
Readme (htm – 87Kb)

via
Autodesk – Autodesk Revit Architecture Services & Support – Hotfix – Autodesk Revit 2012 – Apply material family parameters using the Paint tool