Ren Xiong inscription

[DylanK]

This is from Rén Xióng‘s self-portrait, written in an operatic song-poetry style (昆曲 to be specific). Just wondering what y'all make of the line: 且放歌起舞，当途慢憎颓气。 The first half is clear enough, but what's going on in the second line? I particularly don't understand 憎 in there. So, what do you think? How can that line be understood?

莽乾坤，眼前何物？ 翻笑侧身长系，觉甚事，纷纷攀倚。此则谈何容易！试说豪华，金、张、许、史，到如今能几？还可惜，镜换青娥，尘掩白头，一样奔驰无计。更误人，可怜青史，一字何曾轻记！公子凭虚，先生希有，总难为知己。且放歌起舞，当途慢憎颓气。算少年，原非是想，聊写古来陈例。谁是愚蒙？谁为贤哲？我也全无意。但恍然一瞬，茫茫渺无涯矣！右调《十二时》，任熊渭长倚声。