"my transformer heats up to 60C what could have causing these heat? im using EFD25 Core, i want to lessen the heat dissipation any advice?"
If the core is heating up, you require to lower the flux density. Add more turns, if there is available window area, or increase the core size to increase the magnetic cross section. Or use a higher performance ferrite.
If the wire itself is heating up, you require a larger copper cross section, or litz wire if the frequency is high enough to cause skin effects.