'Hard' in the Bible

Likewise all the men of Israel that had hid themselves in the hill-country of Ephraim, when they heard that the Philistines fled, even they also followed hard after them in the battle.

And the Philistines followed hard upon Saul and upon his sons; and the Philistines slew Jonathan, and Abinadab, and Malchishua, the sons of Saul.