The dynamics of gene expression may impact regulation, and RNA processing can be rate limiting. To assess rates of pre-mRNA splicing, we used a short, progressive metabolic labeling/RNA sequencing strategy to estimate the intron half-lives of ~30,000 fly introns, revealing strong correlations with several gene features. Splicing rates varied with intron length and were fastest for modal intron lengths of 60-70 nt. We also identified hundreds of novel recursively spliced segments, which were associated with much faster and also more accurate splicing of the long introns in which they occur. Surprisingly, the introns in a gene tend to have similar splicing half-lives and longer first introns are associated with faster splicing of subsequent introns. Our results indicate that genes have different intrinsic rates of splicing, and suggest that these rates are influenced by molecular events at gene 5' ends, likely tuning the dynamics of developmental gene expression.