Reproduction steps:
1. Open attached project "compression_regress_unity466" with Unity 4.6
2. Open a copy of the same project with any Unity 5 version
3. Open scene "MainScene" in both projects
4. Compare the edge of the white card with a flag
- The edge looks a lot less blurry in Unity 4 (see attached unity_pvrtc_compression.png)

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Reason for closing as WONTFIX:

We can't fix the PVRTC texture compressor as it comes from imgtec. The work around for this issue is to replace the new compressor binary with the old compressor binary into the installation folder of Unity.

Also, please complain to ImgTec. The more users complain the higher chance they'll fix this issue :-)