TF2 lag spikes

usualy my ping was of 5~10 in a server

now, my ping is 20~30 when the map just begins, and when the doors and the fun starts (everybody shooting at stuff) my ping reaches 150~180

it wasn't like that before the latest patches (of friday)

i need help, tips, understanding what is going on

** my frame per second is cool and constant, that is not the problem (i am not dumb enough for thinking that) **