I've been running a 1.8 Spigot server for a few weeks now, just for my friends, and I've recently been having lots of crashes that cause us to lose progress, but we seem to only lose it in some chunks.
While trying to recreate it, we think that teleporting/flying away too far may be causing some of it, and I think that it also might be caused by one of the people on the server flying 24,000 blocks up for no reason.
I've tried allocating more RAM to the server (up to 16GB with another 16 to run other stuff like a NAS), updating Java, deleting Minecraft and the folders in .appdata then re downloading the msi, and I havn't found a solution.
The Meaning of Life, the Universe, and Everything.
It sounds like you are running this on your computer, would you mind pasting what is inside your run.dat file? (Whatever you use to run the server, it should look something like "java -Xms1G -Xmx2G -jar spigotw18.jar -o true").
Flying 24,000 blocks up would most likely not crash your server anymore than walking around would. If anything you'd be so far away from the ground that the chunks wouldn't be loaded for you therefore saving RAM
I was going to say maybe your computer isn't powerful enough, but I noticed that you have a 4770k.