I have an windows 2012 with SQL 2012 installed, i have an ERP application that has an mdf file of 40 GB , and the actual used space is 26 GB , and the ldf file has 19 GB , but when i query the disk usage it only shows 5 % used. A few months ago the application started to work slow at different intervals ( at about 9 am, 12 PM, 15 PM ) .The server has a 48 GB RAM and 8 cores and the space on HDD is about 180 GB free, i have monitored the servers resources and they all look good, no load that could issue the problem.
I have checked the data base activity monitor and no issues there they all look ok, no load.
I only do a Simple backup, not a full one, so i;m thinking could the problem be from the big transaction log file ?
Any other checks i can do ?