Dialer lags when making a call in Yu Yureka running Lollipop
this update might solve the bug

Update Size: 130Mb Android version: 5.0.2 Software version: Cyanogen OS 12 (YNG1TAS1K0)

"We are excited to announce a new software update for Yureka which will lead to improved battery performance for YUREKA. (with Cyanogen OS 12 YNG1TAS0W0).

This performance update has been rolled out post feedback from our beta testers community and the roll out process starts today.

Over the next few days ALL users who have official Cyanogen OS 12 YNG1TAS0W0 software on their YUREKA, will receive the update."-YuGod

Click here for the original post on yu forum