More efficient non-uniform derandomization ? Adleman, FOCS'78 showed that any randomized circuit for inputs of length $n$ can be non-uniformly derandomized. However, the construction effectively duplicates the original circuit  $O(n)$ times, so the derandomized circuit is larger than the original one by a factor of $O(n)$. Is there any more efficient construction out there that multiplies the circuit size by a smaller factor  ?
I don't think something much better is known.  Because for example, if it were possible to derandomize circuits with only a sublinear blowup, then I think it would also be possible to non-trivially (but non-uniformly*) derandomize communication protocols.  And I don't believe the latter is known.  Adleman's proof gives a linear blowup as you say, so that the derandomization of communication protocols is trivial because it would give a linear blowup in the communication complexity.

*: By "non-uniform" in the context of communication protocols, I mean the algorithm for the two parties to compute the next bit to send to the other is not explicit.  I recall reading a discussion about this in some paper, but I can't seem to find a reference now...