Spiking neural networks target energy-efficient language modeling through sparse, binary activations, but the efficiency-accuracy tradeoff of spiking language models is uncharacterized at scale. We present the first Chinchilla-style IsoFLOP scaling study of a spiking language model, sweeping SpikeGPT-family models (RWKV backbone) from width 384 to 1536 across compute budgets from 3×1017 to 1019 FLOPs on FineWeb-EDU. We report two findings. First, the compute-optimal frontier is Nopt∝C0.56, close to the 0.50 that Hoffmann et al. report for dense Transformers, so spiking does not change how parameters and data should be traded off under a compute budget. Second, against non-spiking RWKV and Transformer baselines trained the same way, the loss gap splits into a backbone cost of about 0.16 nats that does not change with compute and a spiking cost that falls from 0.34 to about 0.23 nats and then levels off. These results give the first compute-optimal recipe for spiking language models and quantify the accuracy cost of their sparsity.
Figures & tables
Figure 1: (a) IsoFLOP profiles: validation loss L versus model size N at each compute budget C , with an interior compute-optimal minimum per tier. (b) The same runs as learning curves (loss versus compute C=6N\ED , colored by budget); their lower envelope is the compute-optimal frontier Lopt(C) , which extrapolates a decade beyond the fit grid to the out-of-sample hero run at C=1020 (measured 2.76 vs. predicted 2.78 nats).
Convention
N
α (IsoFLOP)
α (Approach 3)
D/N ( 3×1017→1019 )
Strict non-embedding (Kaplan)
13ld2
0.748
0.745
25.1→4.7
FLOP-matmul (grid build)
13ld2+vd
0.624
0.644
9.2→4.1
Total (Chinchilla, primary)
13ld2+2vd
0.556
0.595
4.9→3.5
Table 1: Compute-optimal exponent α ( Nopt∝Cα ) under three parameter-counting conventions, estimated in two ways: the IsoFLOP vertex fit (Sec. 4.1 ) and a Chinchilla Approach 3 parametric fit L=E+A/Na+B/Db (Appendix G ). The two estimators agree within each convention. D/N is the compute-optimal token-to-parameter ratio at the smallest and largest budget using IsoFLOP fit.
Figure 2: Spiking RWKV compared with non-spiking baselines. (a) Compute-optimal loss Lopt(C) for each architecture. (b) Backbone cost (dense RWKV minus Transformer) and spiking cost (spiking minus dense RWKV) at each budget.
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
C (FLOPs)
Transformer
Dense RWKV
Spiking RWKV
backbone cost
spiking cost
3×1017
3.195
3.363
3.701
0.168
0.338
1×1018
3.012
3.177
3.441
0.166
0.263
3×1018
2.878
3.030
3.256
0.151
0.227
1×1019
2.671
2.835
3.061
0.164
0.225
Appendix
Table 2: Compute-optimal loss Lopt (nats) for spiking RWKV and the two non-spiking baselines (Section 4.5 ), with backbone cost (dense RWKV minus Transformer) and spiking cost (spiking minus dense RWKV). All runs share data, batch size, schedule, and evaluation; the learning rate is tuned per architecture. The 1019 dense RWKV fit includes a width- 2048 run above the compute-optimal size.
Compute budget C (FLOPs)
d / l
N
3×1017
1×1018
3×1018
1×1019
384/10
57.8M
3.8049
3.7049
–
–
512/12
92.4M
3.7002
3.5283
3.4866
–
640/14
138.9M
3.7384
3.4413
3.3480
3.3141
768/18
215.2M
3.8867
3.4621
3.2978
3.2030
1024/20
375.6M
–
3.5627
3.2558
3.1041
Appendix
Table 3: Final validation loss across the IsoFLOP grid. N is the total parameter count. d is the embedding dimension. l is the number of layers. Bold marks the per-tier minimum; dashes indicate configurations outside the grid at that budget.
C (FLOPs)
Nopt
Dopt
D/N
Lopt
3×1017
101M
0.49B
4.9
3.7014
1×1018
175M
0.95B
5.5
3.4406
3×1018
349M
1.43B
4.1
3.2564
1×1019
693M
2.40B
3.5
3.0619
Appendix
Table 4: Compute-optimal allocation from the IsoFLOP parabola vertices (total parameters).
Figure 3: Fitted learning-rate power law for SpikeGPT.
Dropped tier
α
αtotal
c3e17
0.674
0.615
c1e18
0.616
0.553
c3e18
0.625
0.560
c1e19
0.605
0.532
Full-data
0.624
0.556
Jackknife mean
0.630±0.046
0.565±0.053
Appendix
Table 5: Leave-one-group-out jackknife on the IsoFLOP tiers.
Figure 4: Mean block spike rate versus tokens per parameter; width curves collapse onto one trend.