  Let $D,X \in B(H)$ be bounded operators on an infinite dimensional Hilbert
space $H$. If the commutator $[D,X] = DX-XD$ lies within $\varepsilon$ in
operator norm of the identity operator $1_{B(H)}$, then it was observed by Popa
that one has the lower bound $\| D \| \|X\| \geq \frac{1}{2} \log
\frac{1}{\varepsilon}$ on the product of the operator norms of $D,X$; this is a
quantitative version of the Wintner-Wielandt theorem that $1_{B(H)}$ cannot be
expressed as the commutator of bounded operators. On the other hand, it follows
easily from the work of Brown and Pearcy that one can construct examples in
which $\|D\| \|X\| = O(\varepsilon^{-2})$. In this note, we improve the
Brown-Pearcy construction to obtain examples of $D,X$ with $\| [D,X] - 1_{B(H)}
\| \leq \varepsilon$ and $\| D\| \|X\| = O( \log^{5} \frac{1}{\varepsilon} )$.
