Reactive synthesis is an automated process for deriving correct-by-construction reactive systems from temporal specifications. GR(1), in particular, is a popular LTL fragment that balances efficient synthesis complexity and expressiveness. In this paper, we present a set of novel heuristics to further improve the performance of GR(1) realizability checking and related algorithms, motivated by several observations. These heuristics include (1) discarding intermediate memory not required for many GR(1) algorithms, (2) setting good initial orders of variables and justice constraints, (3) improving the embedding of finite automata into GR(1) when supporting advanced language constructs, and (4) algorithm-specific heuristics for additional GR(1) analyses such as non-well-separation and inherent vacuity detection. We implemented these heuristics in the Spectra synthesizer, and extensively validated and evaluated them on well-known benchmarks consisting of hundreds of specifications. Our results show major performance gains, in particular, an average of realizability checking at least two times faster than the baseline.