I am not pretty sure about why is your ASUS laptop is running slow. But I can mention some points which may be responsible for your laptop to be slow:
# Scan for malware and viruses, until you find some virus for first time.
# Clean your hard drive by removing some junk file like temp files, error data.
# Start disk defragmenter, sometime c drive get heavily defragmented while defragmenting disable your antivirus.
# Sometime you need to increase the capacity of RAM.