Why does my motorcycle ride differently after i hit a high RPM?

i notice that when i leave my job, (which is on the highway) i pull out and hit 8k RPMs sometimes to go 60mph on my 250 ninja, and when i come to my exit and speed is reduced to 35/40mph, the bike sounds, and feels different then it does if i never hit those high speeds first. it feels more…“tense?” like its working harder for some reason. its a 2006 bike with only 1200 miles on it so i dont see it being engine problems or even a problem at all. its my first bike, and maybe this is normal, and its supposed to feel that way. Just wondering. any info is helpful! Thanks!