MTK-generated ODEFunction evaluates more slowly than hand-written function

[vyudu]

Seems like the MTK-generated is ~5x slower than a corresponding hand-written function

using ModelingToolkit
using BenchmarkTools
using SciMLBase
t = ModelingToolkit.t_nounits; D = ModelingToolkit.D_nounits

@parameters α β γ δ
@variables x(t) y(t)
    
eqs = [D(x) ~ α * x - β * x * y,
       D(y) ~ -γ * y + δ * x * y]
    
@mtkbuild sys = ODESystem(eqs, t)
f1 = ODEFunction(sys)
f2 = ODEFunction(sys; eval_expression = true)
f3 = ODEFunction{true, SciMLBase.FullSpecialize}(sys)
f4 = ODEFunction{true, SciMLBase.FullSpecialize}(sys; eval_expression = true)

function lotkavolterra!(du, u, p, t) 
    du[1] = p[1]*u[1] - p[2]*u[1]*u[2]
    du[2] = -p[4]*u[2] + p[3]*u[1]*u[2]
end

du = zeros(2); u = rand(2); p = rand(4); t_ = 0.

@btime f1(du,u,p,t_) # 93.335 ns
du = zeros(2)
@btime f2(du,u,p,t_) # 92.068 ns
du = zeros(2)
@btime f3(du,u,p,t_) # 88.889 ns
du = zeros(2)
@btime f4(du,u,p,t_) # 85.842 ns
du = zeros(2)
@btime lotkavolterra!(du,u,p,t_) # 17.368 ns