Levin's universal algorithm is an algorithm such that $t(U,A) < s_V t(V,A) + t_V$. By modifying the algorithm (see for example Hutter's [The Fastest and Shortest Algorithm for All Well-Defined Problems][1]), you can make $s_V$ a universal constant, though definitely not $1$ as you require. For related work, consult work by Hirsch, Itsykson and their students, for example [this technical report][2].


  [1]: ftp://ftp.idsia.ch/pub/techrep/IDSIA-16-00.ps.gz
  [2]: http://eccc.hpi-web.de/report/2011/091/