First of all, toilets have an integral trap.  That means that the trap is built right into the porcelain of the toilet.  There is not a trap separate from the toilet under the floor.  A sink, basin, bathtub have external traps which are added to the fixture by the installer.

A "Lazy" flush can be the result of several conditions;

1. Toilet tank on the back of toilet is not filling up enough to create proper discharge to the toilet bowl to start ideal flushing action.
   The ballcock or fill valve may need adjusting to raise the water level in the tank – be sure not to raise water level too much, causing water to run down the bowl refill pipe constantly.
2. Flushing rim holes located under the toilet bowl rim may be plugged – use a mirror to look up under the bowl rim to inspect holes. If needed, clean holes with semi-rigid piece of bare wire or solder.
   NOTE:  holes are on a horizontal angle to help start swirling action.
3. Foreign item stuck in integral toilet trap. During my years of plumbing, I have seen a wide variety of objects plug or partially plug a toilet trap. Most of the time they are lodged at the top of the trap, out of sight. How they got into the toilet bowl – Your guess is as good as mine. Sometimes it may be a child flushing a pencil, pen, firetruck, etc. or something falling into the toilet bowl during the flushing cycle from a shelf or pocket.
   However, if just the right size they will flush but not pass thru the toilet trap.
   To view the top of the trap without removing the toilet, you can try removing the water from the bowl, insert a mirror that fits right down into the bottom of the bowl, angle it to show you the op of the trap while shining a flashlight into mirror to light-up your view.  
   If the item is located, you should be able to retrieve it using a metal coat hanger, etc. with a hook bent on it.
   I once had a toilet that would flush good two or three time in a row and then on the following flush it was a lazy flush.  With the mirror and flashlight trick, I was able to see that it was a deodorant Speed Stick which had lodged perfectly, but would pivot back and forth causing the inconsistent flush.  Retrieved it with a bent coat hanger and all was good. 
   There are many other reasons a toilet can cause you grief which could involve drain configuration and venting.
4. Another cause of “Lazy” flushing toilet, gurgling or just poor performance of drain work could be the result of a restricted or closed main plumbing vent.
   During the winter months the 3” or 4” vent extending thru your roof can become restricted by “Hoar Frost”.  As your plumbing system vents warm air thru your vent stack, it produces frost inside the vent above the roof as it hits much colder air.  Eventually this can close-up the main vent causing poor plumbing performance.  To remedy this situation, you either have to go on the roof and clear the vent stack 
   (Be Careful) or install a vent stack heater cable, which I believe are available.
   I won’t quote cost or name brands but may be worth investigating for a permanent fix.