I was trying to exit a town today, and found a bug. Although when you place a block in a protected place it immediately dissapears, it apeears that you can still go on top of the disallawoed block for just enough time to help you jump up from it (in my case allowing me to scale the town wall. In the example the sand block is part of the town. Normally i would be unable to scale that wall by jumping. but jumping on the sand, then puting a block on it, then jumping again from that, i managed to go ontop of the wall. probably nothing major. screensots follow Spoiler
This isn't a bug. The block takes a second to disappear thus allowing you to jump on top of it for a fraction of that time. Nothing will be done to fix this.
Coterie-craft, A similar to default pack. I assure you that higher resolution texture packs are not the reason for this block lag.